Indian Patents. 231045:A PROCESS FOR THE PREPARATION OF LiBF4

Title of Invention	A PROCESS FOR THE PREPARATION OF LiBF4
Abstract	A process for the preparation of LiBF4 which comprises reacting LiBO2 compound with 10 to 48 % hydrofluoric acid (HF) solution at ambient temperature, concentrating the product and recrystallising to obtain high purity LiBF4.

Full Text	Field of the invention The present invention relates to a process for the preparation of LiBF4. Background of the invention LiBF4 has very useful applications in high voltage lithium primary/secondary cells. LiBF4 is well known as a battery electrolyte. This compound was earlier prepared by procedures, which were cumbersome and the yield was poor. The purity of the sample prepared was poor and needed recrystallization. US Patent No. 5,079,109 discloses the use of LiBF4 as a non-aqueous electrolyte for a lithium battery. While several methods are known for the preparation of LiBF4 in the prior art such methods sutTer from the following disadvantages: 1. The purity of the product is low 2. The yield of the product is low 3. Ambient temperature reaction for the product yield 4. Side reactions occur 5. Multiplicity of steps are required. Objects of the invention The main object of this invention is to prepare LiBF4 by a simple chemical reaction. Another object of the invention is to obtain LiBF4 with high yield. A further object of the invention is to obtain LiBF4 by an efficient process. The process of the invention overcomes the disadvantages of the prior art enumerated above. Summary of the invention Accordingly the present invention relates to a process for the preparation of LiBF4 which comprises reacting LiBO2 compound with 10 to 48 % hydrofluoric acid (HF) solution at ambient temperature, concentrating the product and recrystallising to obtain high purity LiBF4. In one embodiment of the invention, LiBO2 is suspended in aqueous media/nonaqueous media and reacted with HF. In a further embodiment of the invention, a paste of LiBO2 is added in HF. In another embodiment of the invention, LiB02 is pasted with water and reacted with HF. Detailed description of the invention In the present invention LiBF4 is prepared by treating suspended particles of LiB02 / Li2N204 in aqueous solution or a paste of LiB02 in water with HF. The quantity of LiB02 and HF are calculated for the reaction separately. After the cessation of the reaction the product was concentrated and crystallized. The product formed was examined and confirmed by x-ray and the purity of the sample was examined. A calculated quantity of HF was carefully added to a known weighed quantity of LiB02 in aqueous solution. The reaction was allowed to proceed. When the reaction ceased, the product was concentrated and rccrystallized to get very high purity of the sample. The product was examined for its purity and identified by x-ray. Fig. 1 indicates the x-ray analysis which matches with available literature (Table 1). TABLE-1 (Table Removed) The synthesis of LiBO2 is disclosed in our copending application number 1176DEL2001. Example 1: preparation of LiBO2 Li2CO3(2.96 gm) and B2O3 (2.8 gm) are mixed with heating up to 600°C to obtain LiBO2 with yield of more than 98%. The colour of the product was white and it was obtained in single phase. The single electrode potential of LiBO2 with respect to Li in IM LiClO4in propylene carbonate was 2.99 V. Example 2: preparation of LiBOz Li2OH (1.68 gm) and B2O3 (2.8 gm) are mixed with heating up to 600°C to obtain LiBO2 with yield of more than 98%. The colour of the product was white and it was obtained in single phase. The single electrode potential of LiBO2 with respect to Li in IM LiClO4 in propylene carbonate was 2.99 V. The LiB02 obtained by the processes of both examples 1 and 2 was high and no side reactions occur. Example 3: preparation of LiBF4 LiBO2 and HF were mixed in a mole ratio of 1:4 by taking HF in water in a Teflon container, keeping the temperature at -4°C, slowly adding LiBO2. When the reaction ceases, the mixture is slowly heated upto dryness at about 100°C to obtain dry LiBF4 with a yield of about 95%. The colour of the product was white and the product was obtained in single phase. The single electrode potential of LiBO4 with respect to Li in IM LiClO4 in propylene carbonate was 2.99 v. Example 4: preparation of LiBF4 LiBO2 and HF were mixed in a mole ratio of 1:4 by taking HF in alcoholic solvent in a Teflon container, keeping the temperature at -4°C, slowly adding LiBO2. When the reaction ceases, the mixture is slowly heated upto dryness at about 100°C to obtain dry LiBF4 with a yield of about 95%. The colour of the product was white and the product was obtained in single phase. The equivalent conductance of LiBF4 in 1 molar PC at 30°C was 34.0 ohm"1cm2mole-1. In the present invention the following advantages are claimed for the synthesis of LiBF4: 1. No side reactions occur 2. A one step procedure is sufficient to prepare this compound 3. Required quantity of the product can be prepared by reacting the calculated quantity of reactants. 4. The product obtained is of high purity 5. The product yield becomes 100 % if the temperature is kept at -4°C. 6. Wetting of LiBO2 prevents evaporation of BF4 formed during the reaction. We claim 1. A process for the preparation of LiBF4 which comprises reacting LiBO2 compound with 10 to 48 % hydrofluoric acid (HF) solution at ambient temperature, concentrating the product and recrystallising to obtain high purity LiBF4. 2. A process as claimed in claim 1 wherein LiBO2 is suspended in aqueous media/nonaqueous media and reacted with HF. 3. A process as claimed in claim 1 wherein LiBO2 is pasted with water and reacted with HF. 4. A process as claimed in claim 1 wherein a paste of LiBO2 is added in HF. 5. A process for the preparation of LiBF4 substantially as described hereinbefore and with reference to the foregoing examples and the accompanying drawing.

Full Text

Field of the invention
The present invention relates to a process for the preparation of LiBF4. Background of the invention
LiBF4 has very useful applications in high voltage lithium primary/secondary cells. LiBF4 is well known as a battery electrolyte. This compound was earlier prepared by procedures, which were cumbersome and the yield was poor. The purity of the sample prepared was poor and needed recrystallization.
US Patent No. 5,079,109 discloses the use of LiBF4 as a non-aqueous electrolyte for a lithium battery.
While several methods are known for the preparation of LiBF4 in the prior art such methods sutTer from the following disadvantages:
1. The purity of the product is low
2. The yield of the product is low
3. Ambient temperature reaction for the product yield
4. Side reactions occur
5. Multiplicity of steps are required.
Objects of the invention
The main object of this invention is to prepare LiBF4 by a simple chemical reaction.
Another object of the invention is to obtain LiBF4 with high yield.
A further object of the invention is to obtain LiBF4 by an efficient process.
The process of the invention overcomes the disadvantages of the prior art enumerated above. Summary of the invention
Accordingly the present invention relates to a process for the preparation of LiBF4 which comprises reacting LiBO2 compound with 10 to 48 % hydrofluoric acid (HF) solution at ambient temperature, concentrating the product and recrystallising to obtain high purity LiBF4.
In one embodiment of the invention, LiBO2 is suspended in aqueous media/nonaqueous media and reacted with HF.
In a further embodiment of the invention, a paste of LiBO2 is added in HF.

In another embodiment of the invention, LiB02 is pasted with water and reacted with HF. Detailed description of the invention
In the present invention LiBF4 is prepared by treating suspended particles of LiB02 / Li2N204 in aqueous solution or a paste of LiB02 in water with HF. The quantity of LiB02 and HF are calculated for the reaction separately. After the cessation of the reaction the product was concentrated and crystallized. The product formed was examined and confirmed by x-ray and the purity of the sample was examined.
A calculated quantity of HF was carefully added to a known weighed quantity of LiB02 in aqueous solution. The reaction was allowed to proceed. When the reaction ceased, the product was concentrated and rccrystallized to get very high purity of the sample. The product was examined for its purity and identified by x-ray. Fig. 1 indicates the x-ray analysis which matches with available literature (Table 1).
TABLE-1
(Table Removed)
The synthesis of LiBO2 is disclosed in our copending application number 1176DEL2001.

Example 1: preparation of LiBO2
Li2CO3(2.96 gm) and B2O3 (2.8 gm) are mixed with heating up to 600°C to obtain LiBO2 with yield of more than 98%. The colour of the product was white and it was obtained in single phase. The single electrode potential of LiBO2 with respect to Li in IM LiClO4in propylene carbonate was 2.99 V. Example 2: preparation of LiBOz
Li2OH (1.68 gm) and B2O3 (2.8 gm) are mixed with heating up to 600°C to obtain LiBO2 with yield of more than 98%. The colour of the product was white and it was obtained in single phase. The single electrode potential of LiBO2 with respect to Li in IM LiClO4 in propylene carbonate was 2.99 V.
The LiB02 obtained by the processes of both examples 1 and 2 was high and no side reactions occur. Example 3: preparation of LiBF4
LiBO2 and HF were mixed in a mole ratio of 1:4 by taking HF in water in a Teflon container, keeping the temperature at -4°C, slowly adding LiBO2. When the reaction ceases, the mixture is slowly heated upto dryness at about 100°C to obtain dry LiBF4 with a yield of about 95%. The colour of the product was white and the product was obtained in single phase. The single electrode potential of LiBO4 with respect to Li in IM LiClO4 in propylene carbonate was 2.99 v. Example 4: preparation of LiBF4
LiBO2 and HF were mixed in a mole ratio of 1:4 by taking HF in alcoholic solvent in a Teflon container, keeping the temperature at -4°C, slowly adding LiBO2. When the reaction ceases, the mixture is slowly heated upto dryness at about 100°C to obtain dry LiBF4 with a yield of about 95%. The colour of the product was white and the product was obtained in single phase. The equivalent conductance of LiBF4 in 1 molar PC at 30°C was 34.0 ohm"1cm2mole-1.
In the present invention the following advantages are claimed for the synthesis of LiBF4:
1. No side reactions occur
2. A one step procedure is sufficient to prepare this compound

3. Required quantity of the product can be prepared by reacting the calculated
quantity of reactants.
4. The product obtained is of high purity
5. The product yield becomes 100 % if the temperature is kept at -4°C.
6. Wetting of LiBO2 prevents evaporation of BF4 formed during the reaction.

We claim
1. A process for the preparation of LiBF4 which comprises reacting LiBO2 compound with
10 to 48 % hydrofluoric acid (HF) solution at ambient temperature, concentrating the
product and recrystallising to obtain high purity LiBF4.
2. A process as claimed in claim 1 wherein LiBO2 is suspended in aqueous
media/nonaqueous media and reacted with HF.
3. A process as claimed in claim 1 wherein LiBO2 is pasted with water and reacted with
HF.
4. A process as claimed in claim 1 wherein a paste of LiBO2 is added in HF.
5. A process for the preparation of LiBF4 substantially as described hereinbefore and with
reference to the foregoing examples and the accompanying drawing.

Documents:

1293-del-2001-abstract.pdf

1293-del-2001-claims.pdf

1293-del-2001-correspondence-others.pdf

1293-del-2001-correspondence-po.pdf

1293-del-2001-description (complete).pdf

1293-del-2001-form-1.pdf

1293-del-2001-form-18.pdf

1293-del-2001-form-2.pdf

1293-del-2001-form-3.pdf

1293-del-2001-petition-138.pdf

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Patent Number

231045

Indian Patent Application Number

1293/DEL/2001

PG Journal Number

13/2009

Publication Date

27-Mar-2009

Grant Date

28-Feb-2009

Date of Filing

28-Dec-2001

Name of Patentee

COUNCIL OF SCIENTIFIC AND INDUSTRIAL RESEARCH

Applicant Address

RAFI MARG, NEW DELHI- 110 001, INDIA

Inventors:

#	Inventor's Name	Inventor's Address
1	ANGAIAH SUBRAMANIAN	EXTENDED SRF, DEPT OF INDUSTRIAL CHEMISTRY, ALAGAPPA UNIVERSITY, KARAIKUDI 630 003, TAMILNADU, INDIA
2	ARIYANAN MANI	CENTRAL ELECTROCHEMICAL RESEARCH INSTITUTE, KARAIKUDI 630 006, TAMIL NADU, INDIA
3	RAMAIYER GANGADHARAN	EMERITUS SCIENTISTS, ALGAPPA UNIVERSITY, KARAIKUDI 630 003, TAMIL NADU, INDIA
4	THIAGARAJAN VASUDEVAN	PROF. & HEAD, ALGAPPA UNIVERSITY, KARAIKUDI 630 003, TAMILNADU, INDIA

PCT International Classification Number

PCT International Application Number

N/A

PCT International Filing date

PCT Conventions:

#	PCT Application Number	Date of Convention	Priority Country
1			NA