CN1171368A

CN1171368A - Process for synthesizing fluoric lithium salt by airflow reaction

Info

Publication number: CN1171368A
Application number: CN 96118728
Authority: CN
Inventors: 王德贵; 黄力; 张宝川; 党海军
Original assignee: Northwest Institute of Nuclear Technology
Current assignee: Northwest Institute of Nuclear Technology
Priority date: 1996-07-18
Filing date: 1996-07-18
Publication date: 1998-01-28
Anticipated expiration: 2016-07-18
Also published as: CN1049407C

Abstract

An airflow reaction process for synthesizing fluorine-contained lithium salt includes such technological steps as putting dry LiF on the tray in airflow reactor, then vacuumizing, introducing anhydrous HF at normal temp. to generate LiHF2, heating to 160-250 deg. C, vacuumizing to remove HF and obtain porous LiF, cooling to 80-100 deg. C, introducing fluoride to generate fluorine-contained lithium salt, and freezing un-reacted fluoride for recovering it in steel cylinder. Its extraction process can be repeated, resulting in low cost and saving time.

Description

A kind of airflow reaction synthesis method of fluorine-containing lithium salts

The present invention relates to a kind of halid preparation method of lithium, the airflow reaction synthesis method of a kind of fluorine-containing lithium salts of more specifically saying so.

Hexafluoro phosphorus lithium LiPF ₆, tetrafluoro boron lithium LiBF ₄With hexafluoro arsenic lithium LiAsF ₆Etc. fluorine-containing lithium salts is electrolyte for Lithium Battery raw material in the battery industry.The domestic document announcement that has not yet to see synthetic this compounds, the method for synthetic this compounds mainly contains following two kinds at present in the world: first kind is that LiF is dissolved in HF, feeds gaseous state 3～5 family's fluorochemicals in solution, promptly gets product after the reaction.Its shortcoming is to carry out in solvent because of synthetic method, and it is rotten easily to introduce the impurity such as HF, moisture content, metal oxide, metal oxyfluoride and the easy moisture absorption of product.Second kind is the disclosed hexafluoro phosphorus of the clear 64-72901 of Japanese Patent JP lithium production method, and this method is that LiF is handled with anhydrous HF, forms vesicular LiF, feeds PF then ₅React, obtain thick product, use the organic solvent purifying at last.But its shortcoming is: 1. purification step need use a large amount of organic solvents, and cost is improved; 2. the organic solvent of using as purifying requires not moisturely, must increase the organic solvent step that dewaters like this, the promptly time-consuming cost that increases again; 3. because the product water absorbability is strong, should not in air, carry out during purifying, increase the purifying difficulty; 4. in the purge process, easily introduce impurity.

The airflow reaction synthesis method that the objective of the invention is to overcome the shortcoming of above-mentioned prior art and a kind of fluorine-containing lithium salts is provided, the product impurity that adopts this method to produce is few, synthetic yield is high and need not use that technology difficulty is big, the higher organic solvent purification step of cost.

For finishing above-mentioned purpose, technical solution provided by the present invention is; A kind of airflow reaction synthesis method of fluorine-containing lithium salts at first places exsiccant LiF on the pallet of airflow reaction device, then, 1. system is vacuumized, and at room temperature feeds anhydrous HF, makes LiF and HF reaction generate LiHF ₂2. reactor is warming up to 160～250 ℃, and vacuumizes, make LiHF ₂Take off HF and obtain vesicular LiF; 3. temperature of reactor is reduced to 80～100 ℃, feed PF ₅Or BF ₃Or AsF ₅, make it generate LiPF ₆Or LiBF ₄Or LiAsF ₆, with unreacted PF ₅Or BF ₃Or AsF ₅Again freeze back steel cylinder; Special character of the present invention is, and is last, with 1. above-mentioned～3. go on foot operation to repeat.

The applicant after deliberation, think after analyzing, with 1. above-mentioned～when 3. going on foot operation and carrying out one time, fluorine-containing lithium salts LiPF ₆, LiBF ₄, LiAsF ₆The reason that productive rate is lower is that the generation because of fluorine-containing lithium salts makes the LiF surface produce the fine and close solid film of one deck, thereby makes PF ₅, BF ₃, AsF ₅Be difficult to be penetrated into inner LiF reaction, finish the synthetic of fluorine-containing lithium salts with the inside.

In addition, the applicant also thinks, with 1. above-mentioned～3. go on foot and also have another chemical process to exist when operation repeats, promptly HF earlier with fluorine-containing lithium salts effect, generate LiPF ₆HF, LiBF ₄HF, LiAsF ₆Adductss such as HF, adducts molecular motion meeting make the HF molecule pass to the LiF molecule of internal layer successively, have quickened LiHF ₂Formation, and the HF in the adducts can take off in temperature-rise period, helps the puffing of layer structure equally, helps the synthetic of fluorine-containing lithium salts.

Repeat 1.～3. to go on foot productive rate or its purity that operation can improve fluorine-containing lithium salts, the multiple number of times is relevant with the fluorine-containing lithium salts purity that need obtain, multiplicity is many more, and the productive rate of the fluorine-containing lithium salts of gained or its purity are also high more, the synthetic LiPF that is carried out with the applicant embodiment 1 ₆Be example, its multiplicity is as follows to the influence of productive rate:

Number of times productive rate (%)

1 30

2 47

3 74

Experimental formula below the relation of 6 86 multiplicity and productive rate is available is represented: productive rate Y (%)=104 * e ^-1.34/n, wherein n is a multiplicity, standard deviation S=5.85%.

Because the needed fluorine-containing lithium salts purity of battery industry generally need be more than 98%, thereby its multiplicity is generally unsuitable very few, but also there is no need too much, and Ying Baozheng makes its fluorine-containing lithium salts that synthesizes can satisfy requirement on the purity.But this multiplicity is not changeless, and along with the difference of processing condition, both having made is for obtaining the product of same purity, and its multiplicity also can change to some extent, and according to the applicant result of test at present, its multiplicity generally need be more than 9 times.

Below will provide several specific examples of the present invention:

Embodiment 1, and at first, the LiF with 509 places on the pallet of the airflow reaction device of being processed by Monel metal; Then, 1. system is vacuumized, feed anhydrous HF at ambient temperature, kept about 30 minutes, make LiF and HF reaction generate LiHF ₂2. reactor is warming up to 170 ℃, kept 1 hour and vacuumized, make LiHF _eTake off HF and obtain cavernous LiF; 3. temperature of reactor is reduced to 100 ℃, feed PF ₅, kept 1 hour, make it generate LiPF ₆, with unreacted PF ₅Again freeze back steel cylinder; At last, with 1. above-mentioned～3. go on foot operation to repeat 9 times, can obtain LiPF ₆, it is shaped as white powder, adopts ICP plasma emission spectroscopy method to measure the Li in the product, P, Fe, Al etc., calculates product purity＞98%, Fe, Al＜1PPm, moisture content＜10PPm.

Embodiment 2, at first, the LiF of 50g placed on the pallet of airflow reaction device; Then, 1. system is vacuumized, feed anhydrous HF at ambient temperature, kept about 30 minutes, make LiF and HF reaction generate LiHF ₂2. reactor is warming up to 190 ℃, kept 50 minutes and vacuumized, make LiHF ₂Take off HF and obtain cavernous LiF; 3. temperature of reactor is reduced to 90 ℃, feed BF ₃, kept 1 hour, make it generate LiBF ₄, the BF of reaction in future ₃Again freeze back steel cylinder; At last, with 1. above-mentioned～3. go on foot operation to repeat 10 times, can obtain the LiBF of purity＞98% ₄

Embodiment 3, at first, the LiF of 50g placed on the pallet of airflow reaction device; Then, 1. system is vacuumized, feed anhydrous HF at ambient temperature, kept about 30 minutes, make LiF and HF reaction generate LiHF _e, 2. reactor is warming up to 230 ℃, kept 40 minutes and vacuumized, make LiHF ₂Take off HF and obtain cavernous LiF; 3. temperature of reactor is reduced to 85 ℃, feed AsF ₅, kept 1 hour, make it generate LiAsF ₆, with unreacted AsF ₅Again freeze back steel cylinder; At last, with 1. above-mentioned～3. go on foot operation to repeat 10 times, can obtain the LiAsF of purity＞98% ₆

Can find out that in conjunction with above-described embodiment the present invention has following advantage compared to existing technology:

1, the present invention adopts the airflow reaction method fully, and reactions steps is wherein repeated, can Be relatively easy to make product purity to reach more than 98%;

2, the present invention has omitted the organic solvent purifying step, has both shortened whole synthesis cycle, has reduced again Production cost;

3, the product that synthesizes because of the present invention does not need to be further purified, and has simplified operating procedure, has reduced Investment has reduced cost;

4, in a reactor, finish whole synthetic reactions, reduced the possibility of polluting, be not easy to introduce Impurity.

Claims

1, a kind of airflow reaction synthesis method of fluorine-containing lithium salts at first places exsiccant LiF on the pallet of airflow reaction device, then, 1. system is vacuumized, and at room temperature feeds anhydrous HF, makes LiF and HF should generate LiHF ₂2. reactor is warming up to 160～250 ℃, and vacuumizes, make LiHF ₂Take off HF and obtain vesicular LiF; 3. temperature of reactor is reduced to 80～100 ℃, feed PF ₅Or BF ₃Or AsF ₅, make it generate LiPF ₆Or LiBF ₄Or LiAsF ₆, with unreacted PF ₅Or BF ₃Or AsF ₅Again freeze back steel cylinder; It is characterized in that: last, with 1. above-mentioned～3. go on foot operation to repeat.

2, the airflow reaction synthesis method of fluorine-containing lithium salts according to claim 1 is characterized in that: described with 1. above-mentioned～3. go on foot operation to repeat to be meant and repeat more than 9 times.