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Preparation method for lithium tetrafluoroborate

A technology of lithium tetrafluoroborate and lithium salt, which is applied in the field of preparation, can solve the problems of increased production cost, complicated purification steps, high cost, etc., and achieve the effects of low production cost, high product purity and stable quality

Active Publication Date: 2016-11-09
LANZHOU UNIVERSITY OF TECHNOLOGY
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Problems solved by technology

[0004] The above methods all use LiF with relatively stable chemical properties as the lithium source. In order to improve the chemical reaction rate and product yield, it is necessary to put forward higher requirements on the specific surface area of ​​LiF, which increases the preparation cost; for LiBF 4 The purification of crude products generally adopts the recrystallization method with low-temperature crystallization steps, and the purification steps are relatively complicated and costly

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  • Preparation method for lithium tetrafluoroborate
  • Preparation method for lithium tetrafluoroborate

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preparation example Construction

[0014] The present invention is a kind of preparation method of lithium tetrafluoroborate, and its steps are:

[0015] (1) Lithium salts containing weak acid radicals, BF 3 Compounds of the class of lithium, boron, and fluorine in a molar ratio of 1:1:4 to 1:2:5 are uniformly mixed in an aprotic, nonpolar or less aprotic polar solvent; wherein the solvent and the lithium element The molar ratio is 3:1~6:1;

[0016] (2) In an air atmosphere, reflux reaction at a temperature of 0°C to 70°C for 1 hour to 24 hours, then carry out solid-liquid separation, and then evaporate the solvent in the obtained liquid at 40°C to 120°C, and dry at 30°C Dry the obtained solid at ~130°C for 5-12 hours to obtain LiBF 4 crude product;

[0017] (3) The resulting solid LiBF 4 The crude product is mixed with the aprotic polar solvent at a mass ratio of 1:1 to 1:10, and after reflux at a temperature of 60°C to 100°C for 1 hour to 12 hours, the solid insoluble matter is separated, and the filtrate...

Embodiment 1

[0023] Add 10 g of lithium carbonate and 100 mL of anhydrous diethyl ether which have been pre-dried at 120 °C for 4 hours in a reactor equipped with a stirrer and stir evenly, then add 24.6 mL of BF 3 ·O(C 2 h 5 ) 2 (BF 3 The concentration is 45% ~ 47%) solution. After reflux reaction at 70°C for 6 hours, filter and separate, then evaporate the solvent in the obtained liquid at 65°C, and dry the obtained solid at 80°C for 6 hours to obtain LiBF 4 crude product. The crude product was dissolved in 100 mL of dimethyl carbonate, stirred and refluxed at 90°C for 3 hours. After the solution was filtered, the solvent was evaporated to dryness at 70° C. and 0.085 Mpa (vacuum degree). Then the obtained solid was washed once with 20 mL of anhydrous ether, and finally dried at 110 °C for 6 hours to obtain LiBF 4product. The product yield is 96.5%. LiBF measured by titration 4 The content of B(III) in the product is 11.48% (mass percentage), close to the theoretical value (11.5...

Embodiment 2

[0025] Into a reactor equipped with a stirrer was added 9 g of Li 2 CO 3 and 100 mL of pretreated fresh anhydrous acetonitrile, into which BF was slowly introduced under stirring conditions 3 Gas, heated to 70°C, refluxed for 14 hours, filtered and separated, then evaporated to dryness of the solvent in the obtained liquid at 95°C, and dried the obtained solid at 130°C for 5 hours to obtain a white solid, which was detected as LiBF 4 crude product. The crude product was dissolved in 100 mL propionitrile, stirred and refluxed at 70°C for 3 hours. After the solution was filtered, all the solvent was evaporated at 80°C and 0.08 MPa (vacuum degree) to obtain a solid. Wash with 20 mL of anhydrous diethyl ether twice under the action of suction filtration. Dry the washed product at 120°C for 8 hours to obtain LiBF 4 product. After repeating the above purification process once, LiBF was measured by titration 4 The content of B(III) in the product is 11.50% (mass percentage), c...

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Abstract

The invention provides a preparation method for lithium tetrafluoroborate. The preparation method comprises the following steps: uniformly mixing compounds containing lithium weak acid salts and BF3 in an aprotic nonpolar or aprotic slightly-polar solvent according to a mol ratio of lithium to boron to fluorine of 1: 1: 4 to 1: 2: 5, wherein a mol ratio of the solvent to element is 3: 1 to 6: 1; carrying out a reflux reaction at 0 to 70 DEG C for 1 to 24 h and then carrying out solid-liquid separation; and drying the solvent in the liquid obtained in the previous step through distillation so as to obtain a crude solid LiBF4 product. As the crude solid LiBF4 product is subjected to purification and separation once, a LiBF4 product has yield of 96% or above and purity of 99% or above; and after purification and separation a plurality of times, the purity of the LiBF4 product can be further improved.

Description

technical field [0001] The invention relates to a preparation technology used as an electrolyte of an electrochemical device such as a lithium ion battery. Background technique [0002] LiBF 4 It is an important lithium salt and additive in the electrolyte of lithium-ion batteries. It has good thermal stability and is more sensitive to moisture than LiPF 6 Low, but also has excellent low temperature performance, has a good market prospect. If a simple process can be used to prepare LiBF that meets the requirements of lithium-ion battery electrochemical devices 4 , and can be produced industrially, which will greatly save production costs and improve LiBF 4 market competitiveness of products and electrochemical devices such as lithium-ion batteries. [0003] Current representative LiBF 4 The preparation methods mainly include: (1) Airflow reaction synthesis method: dry LiF is placed in an airflow reactor, and anhydrous HF is introduced into anhydrous HF at room temperatu...

Claims

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Application Information

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IPC IPC(8): C01B35/06
CPCC01B35/063C01P2002/72
Inventor 崔孝玲薛宇宙李春雷李世友耿珊张宇雷丹
Owner LANZHOU UNIVERSITY OF TECHNOLOGY
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