Title of Invention	"A PROCESS FOR THE PREPARATION OF LITHIUM CHROMIUM MANGANATE (LiCrMnO4) USEFUL AS BATTERY CATHODE MATERIAL FOR LITHIUM ION CELLS"
Abstract	A process for the preparation of lithium chromium magnate (LiCrMnC4) for battery cathode material for lithium ion cells which comprises: preparing a paste by mixing equivocal quantity of (1) lithium salt selected from lithium carbonate, lithium nitrate, (2) a chromium source selected from ammonium chromate, chromic acid and (3) a manganese salt selected from manganese nitrate and manganese carbonate, along with a flux and binding agent such as herein described, followed by heating the above said paste material at a temperature in the range of 250 - 800°C for a period of 6 to 12 hrs. to obtain lithium chromium magnate (LiCrMnO4).

Title of Invention

"A PROCESS FOR THE PREPARATION OF LITHIUM CHROMIUM MANGANATE (LiCrMnO4) USEFUL AS BATTERY CATHODE MATERIAL FOR LITHIUM ION CELLS"

Abstract

A process for the preparation of lithium chromium magnate (LiCrMnC4) for battery cathode material for lithium ion cells which comprises: preparing a paste by mixing equivocal quantity of (1) lithium salt selected from lithium carbonate, lithium nitrate, (2) a chromium source selected from ammonium chromate, chromic acid and (3) a manganese salt selected from manganese nitrate and manganese carbonate, along with a flux and binding agent such as herein described, followed by heating the above said paste material at a temperature in the range of 250 - 800°C for a period of 6 to 12 hrs. to obtain lithium chromium magnate (LiCrMnO4).

Full Text	This invention relates to a process for the preparation of lithium chromium manganate (LiCrMnO4 ) useful as brttery cathode material for lithium ion cells. This invention relates to a novel wet grinding procedure for the preparation of lithium chromium manganate (LiCrMnO4) battery cathode material for rocking chair or lithium ion cells. A novel method of preparing LiCrMnO4 was developed by uniform mixing of carbonates of lithium and manganese with chromic acid or nitrate of lithium and manganese with ammonium chromate of an appropriate composition and this mixture was made into a paste by adding necessary quantity of glycerol and the paste was subjected to heating followed by annealing. The present invention, describes the method of synthesis of the cathode material viz. LiCrMnCU for a secondary battery, by heating a paste prepared by mixing fine particles of carbonates of lithium and manganese with chromic acid in glycerol to made into a paste. This paste was initially heated slowly in a furnace to evaporate off glycerol in order to get a dried mass at 250CC . This dried mass was then continuously heated in between 500- 800°C for 12 hrs. The product formed was slowly cooled to room temperature and was ground well and then examined for its particles size, colour and XRD exposure for purity and structure. It was found that the prepared sample was black in colour and was homogeneous. X- ray analysis confirmed the formation of LiCrMnO4 according to Fig 1. The compound, lithium chromium manganate (LiCrMnC4) is a spinel structured compound which has a property to intercalate small cations like lithium and hence this material when used as a cathode in an electrochemical energy device, it gives high voltage and can be charged & discharged with lithium ions. Thus LiCrMnO4 cathode material behaves like a secondary cell with high energy density. Lithium chromium manganate as a cathode material for intercalation purposes on lithium ion batteries is of recent origin and a few methods are available to prepare this compound. This compound on intercalation as a cathode in conjection with a suitable cathode shows voltages as high as 4.6 and above. Such a cell of high voltage is expected to give high energy density batteries. Hence , the synthesis of this compound by a simple method will be useful to prepare cathode easily and cheaply. Reference may be made to prepare spinel LiCrMnO4 compound is known from the recent literature cited in 1995 as a battery cathode for high voltage lithium cells. This compound was prepared by mixing Li2Co3, Cr2O3 and MnCO3 together and was fired in air initially at 750°C for 24hrs and was subjected to two successive and identical grinding and annealing treatments. [C.Sigala, D.Guyomard and M. Tournoux, Solid State Ionics, 81(1995) 167]. As available in literature LiCrxMn2-xO4 can be alternatively prepared by two methods. In the first method, Li2CO3, Cr2O3and P- Mno2 powders were ground well, and heated in flow of argon gas at 600°C for 3hrs and then heated at 1000°C for three days. In the second method , LiCrO2 and LiMnO2 were used as the starting materials and the pelletized samples were reacted at 1000° [ I..I.Davidson. R.S.Mc Millan and J.J.Murray, J. Power Sources, 54 (1995) 205] In the above mentioned methods any one of the following disadvantages are observed. Phase purity Intermittent heating Long duration of heating & annealing. Several steps etc. A novel method of preparing LiCrMnO2 was developed by uniform mixing of carbonates of lithium and manganese with chromic acid of an appropriate composition ratio and this mixture was made into a paste by adding necessary quantity of glycerol and the paste was subjected to heating & finally annealing. The present invention, describes the method of synthesis of the cathode material for a secondary battery, by heating a paste prepared by mixing fine particles of carbonates of lithium and manganese with chromic acid in glycerol to made into a paste and this paste was initially heated slowly in a furnace to evaporate off glycerol in order to get a dried mass at 250°C and this dried mass was then continuously heated to 500-600°C for 8- 12 hrs and the product formed was slowly cooled to room temperature and was ground well and then it was examined for its particles size, colour and X-ray exposure for purity and structure. It was found that the prepared sample was black in colour and was homogeneous. X- ray analysis confirmed the formation of LiCrMnO2 according to Fig 1. The main objective of the present invention is to provide a to a process for the preparation of lithium chromium manganate (LiCrMnO2 ) useful as battery cathode material for lithium ion cells which obviates the drawbacks as detailed above. Another object of the present invention is to prepare lithium chromium manganate by wet grinding method or paste procedure. Yet another object of the present invention is to prepare lithium chromium manganate by mixing equimolar proportion of LiCOs ,CrO3 and MnCO3. One of the object is to prepare the product LiCrMnO4 by using LiNO3, ammonium chromate and manganese nitrate in equal ratio. Still another object of the present invention is to prepare lithium chromium manganate by a single step procedure Another object of the invention is to prepare lithium chromium manganate with different fuels which have no influence on the product quality, particle size or performance. Still, yet another object of this invention is to prepare lithium chromium manganate with glycerol which has no influence on the quality, colour or nature of the product even if used in excess. A novel method of preparing LiCrMnO4 was developed by uniform mixing of carbonates of lithium and manganese with chromic acid of an appropriate composition ratio and this mixture was made into a paste by adding necessary quantity of glycerol and the paste was subjected to heating. Accordingly the present invention to a process for the preparation of lithium chromium manganate (LiCrMnO4 ) for battery cathode material for lithium ion cells which comprises : preparing a paste by mixing equimolar quantity of (1) lithium salt selected from lithium carbonate, lithium nitrate, (2) chromium source selected from ammonium chromate, chromic acid and (3) manganese salt selected from manganese nitrate and manganese carbonate along with the flux and binding agent followed by heating the above said paste material at a temperature in the range of 250 - 800 ° C for a period of 6 to 12 hrs. to give LiCrMnO4. In an embodiment of the present invention Li2CO3, CrO3 and MnCO3 was used in equimolar proportion. In another embodiment of the present invention glycerol was used as a binding agent for uniform reaction. In yet another embodiment of the present invention the flux used may be selected from urea glycine, citric acid and ammonium formate. In a feature of the invention the use of flux has no influence on the product quality, purity or colour. In still another embodiment of the present invention is a single step process, since chromic acid is used, the decomposition of salts like Li2CO3 and MnCO3 is easy and hence the purity of the product is high. Pure lithium carbonate, chromic acid and manganese carbonate were taken in equimolar proportions and were ground well in a pestle and mortor arrangement and to this ground mixture 3-5 mi of glyceroi and 5-10 gm of urea were added and the whole mass was made into a paste. This paste was transferred into a silica / porcelain crucible and then kept in a muffle furnace. The furnace was heated initially to 250°C for an hour to dry the paste and has subsequently heated to 600°C for 12 hours constantly. The product was cooled and ground well and the product was analysed by x-ray for identification.The product was black in colour. The process provides a low temperature combustion method for the synthesis of LiCrMnO4 battery cathode material for high voltage lithium - ion cells which comprises by mixing equimolar proportion of LiNOs, Ammonium chromate and Manganese nitrate together in a pestle & mortar arrangement and glycerol was added to the mixture and ground well in order to make a paste and to this paste added two times the weight of urea and the whole paste once again ground well and was transferred to a silica - porcelain crucible and was introduced into a preheated muffle furnace kept at 200°C and the product was dried and then the temperature of the furnace was raised to 600°C and kept for 6 hours till the whole reaction was complete and then cooled the product which is black in colour was examined by x- ray for purity and identity. The following examples are given by way of illustration and therefore should be construed to limit the scope of the present invention. Example-1 Li2CO3 0.84gm, CrO3 2.0gm and MnCO3 2.3gm were mixed with 2ml of glycerol and 3gm of urea and the whole mixture was made into a paste. The paste was transferred into a crucible ( silica/ porcelain) and initially heated to 250°C for dryness and subsequently to 800°C for 12 hours. The product was black in colour. Example-2 Li2CO3 0.84gm, CrO3 2.0gm and MnCO3 2.3gm were mixed with 3ml of glycerol and 3gm of urea and the whole mixture was made into a paste. The paste was transferred into a crucible ( silica/ porcelain) and initially heated to 250°C for dryness and subsequently to 800°C for 12 hours. The product was black in colour. Example-3 Li2CO3 0.84gm, CrO3 2.0gm and MnCO3 2.3gm were mixed with 4ml of glycerol and 3gm of urea and the whole mixture was made into a paste. The paste was transferred into a crucible ( silica/ porcelain) and initially heated to 250°C for dryness and subsequently to 800°C for 12 hours. The product was black in colour. Example-4 Li2CO3 0.84gm, CrO3 2.0gm and MnCO3 2.3gm were mixed with 4ml of glycerol and 4gm of urea and the whole mixture was made into a paste. The paste was transferred into a crucible ( silica/ porcelain) and initially heated to 250°C for dryness and subsequently to 800°C for 12 hours. The product was black in colour. Example-5 Li2CO3 0.84gm, CrO3 2.0gm and MnCO3 2.3gm were mixed with 5ml of glycerol and 4gm of urea and the whole mixture was made into a paste. The paste was transferred into a crucible ( silica/ porcelain) and initially heated to 250°C for dryness and subsequently to 800°C for 12 hours. The product was black in colour. Example-6 LiaCO3 0.84gm, CrOa 2.0gm and MnCCh 2.3gm were mixed with 4ml of glycerol and 4gm of citric acid and the whole mixture was made into a paste. The paste was transferred into a crucible ( silica/ porcelain) and initially heated to 250°C for dryness and subsequently to 800°C for 12 hours. The product was black in colour. Example-7 0.84gm, CrO3 2.0gm and MnCO3 2.3gm were mixed with 4ml of glycerol and 4 gm of ammonium formate and the whole mixture was made into a paste. The paste was transferred into a crucible ( silica/ porcelain) and initially heated to 250°C for dryness and subsequently to 800°C for 8- 12 hours. The product was black in colour. Example-8 LiaCO4 0.84gm, CrO3 2.0gm and MnCO4 2.3gm were mixed with 5ml of glycerol and 4gm of glycine and the whole mixture was made into a paste. The paste was transferred into a crucible ( silica/ porcelain) and initially heated to 250°C for dryness and subsequently to 600°C for 12 hours. The product was black in colour. Example-9 Equimolar quantities of LiNCh, (NH4)2 Cr2O7 and MnNO4 (one mole of each) were mixed with 3 ml of glycerol and glycine as twice the weight of the inorganic salt mixtures and was made into a paste. The paste was kept in crucible and was introduced into a muffle furnace initially heating 250°C for half an hour and subsequently to 600°C for 6 hours. The product was cooled and examined for its colour , quality and particle size. Example-10 Equimolar quantities of LiNOa, (NFL^ C^Oy and MnNOa (one mole of each) were mixed with 4 ml of glycerol and glycine as twice the weight of the inorganic salt mixtures and was made into a paste. The paste was kept in crucible and was introduced into a muffle furnace initially heating 250°C for half an hour and subsequently to 600°C for 6 hours.The product was cooled and examined for its colour , quality and particle size. Example-11 Equimolar quantities of LiNOa, (NH4)2 Cr2O7 and MnNO3 (one mole of each) were mixed with 5 ml of glycerol and glycine as twice the weight of the inorganic salt mixtures and was made into a paste. The paste was kept in crucible and was introduced into a muffle furnace initially heating 250°C for half an hour and subsequently to 600°C for 6 hours.The product was cooled and examined for its colour , quality and particle size. Example-12 Equimolar quantities of LiNOs, (NH4)2 Cr2O7 and MnNO3 (one mole of each) were mixed with 6 ml of glycerol and glycine as twice the weight of the inorganic salt mixtures and was made into a paste. The paste was kept in crucible and was introduced into a muffle furnace initially heating 250°C for half an hour and subsequently to 600°C for 6 hours.The product was cooled and examined for its colour , quality and particle size. Example-13 Equimolar quantities of LiNOa, (NH4)2 Cr2O7and MnNO3 (one mole of each) were mixed with 4 ml of glycerol and urea as twice the weight of the inorganic salt mixtures and was made into a paste. The paste was kept in crucible and was introduced into a muffle furnace initially heating 250°C for half an hour and subsequently to 600°C for 6 hours.The product was cooled and examined for its colour, quality and particle size. Example-14 Equimolar quantities of LiNo3(NH4)2 Cr2O7and MnNO3 (one mole of each) were mixed with 4 ml of glycerol and ammonium formate as twice the weight of the inorganic salt mixtures and was made into a paste. The paste was kept in crucible and was introduced into a muffle furnace initially heating 250°C for half an hour and subsequently to 600°C for 6 hours. The product was cooled and examined for its colour , quality and particle size. Example-15 Equimolar quantities of LiNOs, (NH4)2 Cr2O7(one mole of each) were mixed with 4 ml of glycerol and citric acid as twice the weight of the inorganic salt mixtures and was made into a paste. The paste was kept in crucible and was introduced into a muffle furnace initially heating 250°C for half an hour and subsequently to 600°C for 6 hours. The product was cooled and examined for its colour , quality and particle size. Example-16 Equimolar quantities of LiNO3, (NH4)2 Cr2O7 and MnNO3 (one mole of each) were mixed with 5 ml of glycerol and citric acid as twice the weight of the inorganic salt mixtures and was made into a paste. The paste was kept in crucible and was introduced into a muffle furnace initially heating 250°C for half an hour and subsequently to 600°C for 6 hours. The product was cooled and examined for its colour , quality and particle size Observation ( Examples 1 to 16) 1. Colour of the product viz LiCrMnO4 is black. 2. Particle size is in between 5-10 mµ 3. Spinel structure . 4. Single electrode potential of the cathode material measured with Li electrode in PC containing LiClCu is 3.0 volt. The main advantages of the present invention are : 1. An uniform homogeneous mixture of the reacting components viz, carbonates of lithium and manganese with chromic acid were made into a paste to get a product of high purity. 2. Glycerol was used as a solvent for binding the reacting materials viz, carbonates of lithium and manganese with chromic acid for making a paste of required consistency. The addition of glycerol enhanced the product of fine particles. 3. The excess addition of glycerol (solvent) as a binding material for the reactants does not change the colour or quality of the end product. 4. Since a homogeneously prepared paste was subjected to calcination of the compound leaves all the reactants to react uniformly to get fine resultant product without leaving any unreacted initial components. 5. Since chromic acid is used, the removal of CO2 is easy and hence the purity of the product is high. 6. The procedure for the preparation of LiCrMnO4 is a single step process because of chromic acid; 7. Long time heating is not necessary. We claim : 1 . A process for the preparation of htliium chromium manganate (LiCrMnO4 ) for battery cathode material for lithium ion cells which comprises : preparing a paste by mixing equivocal quantity of (1) lithium salt selected from lithium carbonate, lithium nitrate, (2) a chromium source selected from ammonium chromate, chromic acid and (3) a manganese salt selected from manganese nitrate and manganese carbonate along with a flux and binding agent followed by heating the above said paste material at a temperature in the range of 250 - 800 ° C for a period of 6 to 12 hrs. to obtain LiCrMnO4. 2. A process as claimed in claim -1 where in the temperature of heating ranges between 500°C to 800°C 3. A process as claimed in claims 1 to 2 wherein the glycerol is used a6binding agent which assists the reaction to continue and at the same time prevents side reactions. 4. A process as claimed in claims 1 to 3 wherein the quantity of glycerol as binding agent, quantity of flux like urea, glycine, citric acid etc has no influence on the product viz. Colour, particle size, single electrode potential and purity. 5. A process as claimed in claims 1 to 4 wherein glycerol is used as a binding agent and a paste made out with the reactants prevents side reaction and assists in uniform product formation. 6. A process as claimed in claims 1 - 5 wherein the flux used is selected from urea, glycine, citric acid. 7. A process for preparation of lithium chromium manganate (LiCrMnO4) useful as a battery cathode material for high voltage lithium cells substantially as here in described in the reference to the examples and drawing accompanying the specification.

Full Text

This invention relates to a process for the preparation of lithium chromium manganate (LiCrMnO4 ) useful as brttery cathode material for lithium ion cells. This invention relates to a novel wet grinding procedure for the preparation of lithium chromium manganate (LiCrMnO4) battery cathode material for rocking chair or lithium ion cells. A novel method of preparing LiCrMnO4 was developed by uniform mixing of carbonates of lithium and manganese with chromic acid or nitrate of lithium and manganese with ammonium chromate of an appropriate composition and this mixture was made into a paste by adding necessary quantity of glycerol and the paste was subjected to heating followed by annealing.
The present invention, describes the method of synthesis of the cathode material viz. LiCrMnCU for a secondary battery, by heating a paste prepared by mixing fine particles of carbonates of lithium and manganese with chromic acid in glycerol to made into a paste. This paste was initially heated slowly in a furnace to evaporate off glycerol in order to get a dried mass at 250CC . This dried mass was then continuously heated in between 500- 800°C for 12 hrs. The product formed was slowly cooled to room temperature and was ground well and then examined for its particles size, colour and XRD exposure for purity and structure. It was found that the prepared sample was black in colour and was homogeneous. X- ray analysis confirmed the formation of LiCrMnO4 according to Fig 1.
The compound, lithium chromium manganate (LiCrMnC4) is a spinel structured compound which has a property to intercalate small cations like lithium and hence this material when used as a cathode in an electrochemical energy device, it gives high voltage and can be charged & discharged with lithium ions. Thus LiCrMnO4 cathode material behaves like a secondary cell with high energy density.
Lithium chromium manganate as a cathode material for intercalation purposes on lithium ion batteries is of recent origin and a few methods are available to prepare this compound. This compound on intercalation as a cathode in conjection with a suitable cathode shows voltages as high as 4.6 and above. Such a cell of high voltage is expected to give high energy density batteries. Hence , the synthesis of this compound by a simple method will be useful to prepare cathode easily and cheaply.
Reference may be made to prepare spinel LiCrMnO4 compound is known from the recent literature cited in 1995 as a battery cathode for high voltage lithium cells. This compound was prepared by mixing Li2Co3, Cr2O3 and MnCO3 together and was fired in air initially at 750°C for 24hrs and was subjected to two successive and identical grinding and annealing treatments. [C.Sigala, D.Guyomard and M. Tournoux, Solid State Ionics, 81(1995) 167].
As available in literature LiCrxMn2-xO4 can be alternatively prepared by two methods. In the first method, Li2CO3, Cr2O3and P- Mno2 powders were ground well, and heated in flow of argon gas at 600°C for 3hrs and then heated at 1000°C for three days. In the second method , LiCrO2 and LiMnO2 were used as the starting materials and the pelletized samples were reacted at 1000° [ I..I.Davidson. R.S.Mc Millan and J.J.Murray, J. Power Sources, 54 (1995) 205] In the above mentioned methods any one of the following disadvantages are observed. Phase purity Intermittent heating
Long duration of heating & annealing. Several steps etc.
A novel method of preparing LiCrMnO2 was developed by uniform mixing of carbonates of lithium and manganese with chromic acid of an appropriate composition ratio and this mixture was made into a paste by adding necessary quantity of glycerol and the paste was subjected to heating & finally annealing.
The present invention, describes the method of synthesis of the cathode material for a secondary battery, by heating a paste prepared by mixing fine particles of carbonates of lithium and manganese with chromic acid in glycerol to made into a paste and this paste was initially heated slowly in a furnace to evaporate off glycerol in order to get a dried mass at 250°C and this dried mass was then continuously heated to 500-600°C for 8- 12 hrs and the product formed was slowly cooled to room temperature and was ground well and then it was examined for its particles size, colour and X-ray exposure for purity and structure. It was found that the prepared sample was black in
colour and was homogeneous. X- ray analysis confirmed the formation of LiCrMnO2 according to Fig 1.
The main objective of the present invention is to provide a to a process for the preparation of lithium chromium manganate (LiCrMnO2 ) useful as battery cathode material for lithium ion cells which obviates the drawbacks as detailed above.
Another object of the present invention is to prepare lithium chromium manganate by wet grinding method or paste procedure.
Yet another object of the present invention is to prepare lithium chromium manganate by mixing equimolar proportion of LiCOs ,CrO3 and MnCO3.
One of the object is to prepare the product LiCrMnO4 by using LiNO3, ammonium chromate and manganese nitrate in equal ratio.
Still another object of the present invention is to prepare lithium chromium manganate by a single step procedure
Another object of the invention is to prepare lithium chromium manganate with different fuels which have no influence on the product quality, particle size or performance. Still, yet another object of this invention is to prepare lithium chromium manganate with glycerol which has no influence on the quality, colour or nature of the product even if used in excess.
A novel method of preparing LiCrMnO4 was developed by uniform mixing of carbonates of lithium and manganese with chromic acid of an appropriate composition ratio and this mixture was made into a paste by adding necessary quantity of glycerol and the paste was subjected to heating.
Accordingly the present invention to a process for the preparation of lithium chromium manganate (LiCrMnO4 ) for battery cathode material for lithium ion cells which comprises : preparing a paste by mixing equimolar quantity of (1) lithium salt selected from lithium carbonate, lithium nitrate, (2) chromium source selected from ammonium chromate, chromic acid and (3) manganese salt selected from manganese nitrate and manganese carbonate along with the flux and binding agent followed by heating the above said paste material at a temperature in the range of 250 - 800 ° C for a period of 6 to 12 hrs. to give LiCrMnO4.
In an embodiment of the present invention Li2CO3, CrO3 and MnCO3 was used in equimolar proportion.
In another embodiment of the present invention glycerol was used as a binding agent for uniform reaction.
In yet another embodiment of the present invention the flux used may be selected from urea glycine, citric acid and ammonium formate.
In a feature of the invention the use of flux has no influence on the product quality, purity or colour.
In still another embodiment of the present invention is a single step process, since chromic acid is used, the decomposition of salts like Li2CO3 and MnCO3 is easy and hence the purity of the product is high.
Pure lithium carbonate, chromic acid and manganese carbonate were taken in equimolar proportions and were ground well in a pestle and mortor arrangement and to this ground mixture 3-5 mi of glyceroi and 5-10 gm of urea were added and the whole mass was made into a paste. This paste was transferred into a silica / porcelain crucible and then kept in a muffle furnace. The furnace was heated initially to 250°C for an hour to dry the paste and has subsequently heated to 600°C for 12 hours constantly. The product was cooled and ground well and the product was analysed by x-ray for identification.The product was black in colour.
The process provides a low temperature combustion method for the synthesis of LiCrMnO4 battery cathode material for high voltage lithium - ion cells which comprises by mixing equimolar proportion of LiNOs, Ammonium chromate and Manganese nitrate together in a pestle & mortar arrangement and glycerol was added to the mixture and ground well in order to make a paste and to this paste added two times the weight of urea and the whole paste once again ground well and was transferred to a silica - porcelain crucible and was introduced into a preheated muffle furnace kept at 200°C and the product was dried and then the temperature of the furnace was raised to 600°C and kept for 6 hours till the whole reaction was complete and then cooled the product which is black in colour was examined by x- ray for purity and identity.
The following examples are given by way of illustration and therefore should be construed to limit the scope of the present invention.
Example-1
Li2CO3 0.84gm, CrO3 2.0gm and MnCO3 2.3gm were mixed with 2ml of glycerol and 3gm of urea and the whole mixture was made into a paste. The paste was transferred into a crucible ( silica/ porcelain) and initially heated to 250°C for dryness and subsequently to 800°C for 12 hours. The product was black in colour. Example-2
Li2CO3 0.84gm, CrO3 2.0gm and MnCO3 2.3gm were mixed with 3ml of glycerol and 3gm of urea and the whole mixture was made into a paste. The paste was transferred into a crucible ( silica/ porcelain) and initially heated to 250°C for dryness and subsequently to 800°C for 12 hours. The product was black in colour. Example-3
Li2CO3 0.84gm, CrO3 2.0gm and MnCO3 2.3gm were mixed with 4ml of glycerol and 3gm of urea and the whole mixture was made into a paste. The paste was transferred into a crucible ( silica/ porcelain) and initially heated to 250°C for dryness and subsequently to 800°C for 12 hours. The product was black in colour.
Example-4
Li2CO3 0.84gm, CrO3 2.0gm and MnCO3 2.3gm were mixed with 4ml of glycerol and 4gm of urea and the whole mixture was made into a paste. The paste was transferred into a crucible ( silica/ porcelain) and initially heated to 250°C for dryness and subsequently to 800°C for 12 hours. The product was black in colour. Example-5
Li2CO3 0.84gm, CrO3 2.0gm and MnCO3 2.3gm were mixed with 5ml of glycerol and 4gm of urea and the whole mixture was made into a paste. The paste was transferred into a crucible ( silica/ porcelain) and initially heated to 250°C for dryness and subsequently to 800°C for 12 hours. The product was black in colour.
Example-6
LiaCO3 0.84gm, CrOa 2.0gm and MnCCh 2.3gm were mixed with 4ml of glycerol and 4gm of citric acid and the whole mixture was made into a paste. The paste was transferred into a crucible ( silica/ porcelain) and initially heated to 250°C for dryness and subsequently to 800°C for 12 hours. The product was black in colour. Example-7
0.84gm, CrO3 2.0gm and MnCO3 2.3gm were mixed with 4ml of glycerol and 4 gm of ammonium formate and the whole mixture was made into a paste. The paste was transferred into a crucible ( silica/ porcelain) and initially heated to 250°C for dryness and subsequently to 800°C for 8- 12 hours. The product was black in colour. Example-8
LiaCO4 0.84gm, CrO3 2.0gm and MnCO4 2.3gm were mixed with 5ml of glycerol and 4gm of glycine and the whole mixture was made into a paste. The paste was transferred into a crucible ( silica/ porcelain) and initially heated to 250°C for dryness and subsequently to 600°C for 12 hours. The product was black in colour.
Example-9
Equimolar quantities of LiNCh, (NH4)2 Cr2O7 and MnNO4 (one mole of each)
were mixed with 3 ml of glycerol and glycine as twice the weight of the inorganic salt mixtures and was made into a paste. The paste was kept in crucible and was introduced into a muffle furnace initially heating 250°C for half an hour and subsequently to 600°C for 6 hours. The product was cooled and examined for its colour , quality and particle size. Example-10
Equimolar quantities of LiNOa, (NFL^ C^Oy and MnNOa (one mole of each) were mixed with 4 ml of glycerol and glycine as twice the weight of the inorganic salt mixtures and was made into a paste. The paste was kept in crucible and was introduced into a muffle furnace initially heating 250°C for half an hour and subsequently to 600°C for 6 hours.The product was cooled and examined for its colour , quality and particle size. Example-11
Equimolar quantities of LiNOa, (NH4)2 Cr2O7 and MnNO3 (one mole of each) were mixed with 5 ml of glycerol and glycine as twice the weight of the inorganic salt
mixtures and was made into a paste. The paste was kept in crucible and was introduced into a muffle furnace initially heating 250°C for half an hour and subsequently to 600°C for 6 hours.The product was cooled and examined for its colour , quality and particle size. Example-12
Equimolar quantities of LiNOs, (NH4)2 Cr2O7 and MnNO3 (one mole of each) were mixed with 6 ml of glycerol and glycine as twice the weight of the inorganic salt mixtures and was made into a paste. The paste was kept in crucible and was introduced into a muffle furnace initially heating 250°C for half an hour and subsequently to 600°C for 6 hours.The product was cooled and examined for its colour , quality and particle size. Example-13
Equimolar quantities of LiNOa, (NH4)2 Cr2O7and MnNO3 (one mole of each) were mixed with 4 ml of glycerol and urea as twice the weight of the inorganic salt mixtures and was made into a paste. The paste was kept in crucible and was introduced into a muffle furnace initially heating 250°C for half an hour and subsequently to 600°C for 6 hours.The product was cooled and examined for its colour, quality and particle size. Example-14
Equimolar quantities of LiNo3(NH4)2 Cr2O7and MnNO3 (one mole of each) were mixed with 4 ml of glycerol and ammonium formate as twice the weight of the inorganic salt mixtures and was made into a paste. The paste was kept in crucible and was introduced into a muffle furnace initially heating 250°C for half an hour and subsequently to 600°C for 6 hours. The product was cooled and examined for its colour , quality and particle size.
Example-15
Equimolar quantities of LiNOs, (NH4)2 Cr2O7(one mole of each) were mixed with 4 ml of glycerol and citric acid as twice the weight of the inorganic salt mixtures and was made into a paste. The paste was kept in crucible and was introduced into a muffle furnace initially heating 250°C for half an hour and subsequently to 600°C for 6 hours. The product was cooled and examined for its colour , quality and particle size.
Example-16
Equimolar quantities of LiNO3, (NH4)2 Cr2O7 and MnNO3 (one mole of each) were mixed with 5 ml of glycerol and citric acid as twice the weight of the inorganic salt mixtures and was made into a paste. The paste was kept in crucible and was introduced into a muffle furnace initially heating 250°C for half an hour and subsequently to 600°C for 6 hours. The product was cooled and examined for its colour , quality and particle size Observation ( Examples 1 to 16)
1. Colour of the product viz LiCrMnO4 is black.
2. Particle size is in between 5-10 mµ
3. Spinel structure .
4. Single electrode potential of the cathode material measured with Li electrode in PC
containing LiClCu is 3.0 volt.
The main advantages of the present invention are :
1. An uniform homogeneous mixture of the reacting components viz, carbonates of
lithium and manganese with chromic acid were made into a paste to get a product of
high purity.
2. Glycerol was used as a solvent for binding the reacting materials viz, carbonates of
lithium and manganese with chromic acid for making a paste of required
consistency. The addition of glycerol enhanced the product of fine particles.
3. The excess addition of glycerol (solvent) as a binding material for the reactants does
not change the colour or quality of the end product.
4. Since a homogeneously prepared paste was subjected to calcination of the
compound leaves all the reactants to react uniformly to get fine resultant product
without leaving any unreacted initial components.
5. Since chromic acid is used, the removal of CO2 is easy and hence the purity of the
product is high.
6. The procedure for the preparation of LiCrMnO4 is a single step process because of
chromic acid;
7. Long time heating is not necessary.

We claim :
1 . A process for the preparation of htliium chromium manganate (LiCrMnO4 ) for battery cathode material for lithium ion cells which comprises : preparing a paste by mixing equivocal quantity of (1) lithium salt selected from lithium carbonate, lithium nitrate, (2) a chromium source selected from ammonium chromate, chromic acid and (3) a manganese salt selected from manganese nitrate and manganese carbonate along with a flux and binding agent followed by heating the above said paste material at a temperature in the range of 250 - 800 ° C for a period of 6 to 12 hrs. to obtain LiCrMnO4.
2. A process as claimed in claim -1 where in the temperature of heating ranges
between 500°C to 800°C
3. A process as claimed in claims 1 to 2 wherein the glycerol is used a6binding
agent which assists the reaction to continue and at the same time prevents side reactions.
4. A process as claimed in claims 1 to 3 wherein the quantity of glycerol as binding
agent, quantity of flux like urea, glycine, citric acid etc has no influence on the product
viz. Colour, particle size, single electrode potential and purity.
5. A process as claimed in claims 1 to 4 wherein glycerol is used as a binding agent
and a paste made out with the reactants prevents side reaction and assists in uniform
product formation.
6. A process as claimed in claims 1 - 5 wherein the flux used is selected from urea,
glycine, citric acid.
7. A process for preparation of lithium chromium manganate (LiCrMnO4) useful
as a battery cathode material for high voltage lithium cells substantially as here in
described in the reference to the examples and drawing accompanying the specification.

Documents:

791-del-2001-abstract.pdf

791-del-2001-claims.pdf

791-DEL-2001-Correspondence-Others.pdf

791-del-2001-correspondence-po.pdf

791-del-2001-description (complete).pdf

791-del-2001-drawings.pdf

791-del-2001-form-1.pdf

791-del-2001-form-18.pdf

791-del-2001-form-2.pdf

791-del-2001-form-3.pdf

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Patent Number

220781

Indian Patent Application Number

791/DEL/2001

PG Journal Number

30/2008

Publication Date

25-Jul-2008

Grant Date

05-Jun-2008

Date of Filing

24-Jul-2001

Name of Patentee

COUNCIL OF SCIENTIFIC AND INDUSTRIAL RESEARCH

Applicant Address

Inventors:

#	Inventor's Name	Inventor's Address
1	THIAGARAJAN VASUDEVAN
2	RAMAIYER GANGADHARAN
3	ANGAIAH SUBRAMANIAN

PCT International Classification Number

H01M 4/00

PCT International Application Number

N/A

PCT International Filing date

PCT Conventions:

#	PCT Application Number	Date of Convention	Priority Country
1			NA