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Method for preparing lithium difluorophosphate by flow chemical method

A lithium difluorophosphate, flow chemistry technology, applied in chemical instruments and methods, inorganic chemistry, phosphorus compounds, etc., can solve the problems of reduced yield and purity, unfriendly environment, decomposition, etc., to reduce solvent consumption, The effect of reducing production costs and reducing emissions

Active Publication Date: 2022-01-04
SHENZHEN YANYI NEW MATERIALS CO LTD
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

However, although a microchannel reactor is used for mass transfer and heat transfer reaction, due to the high water content in the system, it is easy to cause the decomposition of lithium hexafluorophosphate and lithium difluorophosphate, and it is difficult to react due to the constant temperature used in the reaction process. Fully improve the reaction efficiency of the microchannel reactor, the lack of process control can not reduce the generation of side reactions, resulting in insufficient reaction, it is difficult to reduce the content of characteristic impurities such as lithium metaphosphate, lithium phosphate, and lithium monofluorophosphate in the product, and the yield and reduced purity
There is no recycling of solvents, etc., the environment is not friendly, and it is difficult to meet the market's requirements for high-purity difluorophosphate
Chinese patent CN110342486A discloses a method for synthesizing lithium difluorophosphate from lithium dihydrogen phosphate and hydrogen fluoride under the action of a fluorination catalyst, but it is not suitable for mass production because it is difficult to remove metal heteroions

Method used

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  • Method for preparing lithium difluorophosphate by flow chemical method
  • Method for preparing lithium difluorophosphate by flow chemical method

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0062] The reaction equation involved in embodiment 1 is as follows:

[0063] LiPF 6 +2(CH 3 ) 3 -Si-O-Si-(CH 3 ) 3 = LiPO 2 f 2 +4(CH 3 ) 3 -Si-F↑

[0064] (1) Dissolve 30.00 g of lithium hexafluorophosphate in 70.00 g of dimethyl carbonate dehydrated by 4A molecular sieves in an ice-water bath at 0°C, stir for 0.5 h, and prepare a dimethyl carbonate solution of lithium hexafluorophosphate with a mass fraction of 30%. Wherein, the moisture content in the dimethyl carbonate detected by Metrohm 917 moisture tester is 15ppm.

[0065] (2) Use a peristaltic pump to preheat the dimethyl carbonate solution of lithium hexafluorophosphate and 70.55 g of hexamethyldisiloxane solution through a heat exchanger to 60 ° C respectively, wherein lithium hexafluorophosphate and hexamethyldisiloxane The molar ratio of Si-O units of alkane is 1:2.2.

[0066] (3) The dimethyl carbonate solution and the hexamethyldisiloxane solution of the preheated lithium hexafluorophosphate enter th...

Embodiment 2

[0072] The reaction equation involved in embodiment 2 is as follows:

[0073] LiPF 6 +0.5C 8 h 24 o 4 Si 4 = LiPO 2 f 2 +2(CH 3 ) 2 -Si-F2↑

[0074] (1) Dissolve 20.00 g of lithium hexafluorophosphate in 80.00 g of ethyl methyl carbonate dehydrated by 4A molecular sieves in a water bath at 5°C, stir for 0.5 h, and prepare a 20% lithium hexafluorophosphate solution in ethyl methyl carbonate. Wherein, the moisture content in ethyl methyl carbonate detected by Metrohm 917 moisture tester is 45ppm.

[0075] (2) Use a peristaltic pump to preheat the above-prepared lithium hexafluorophosphate ethyl methyl carbonate solution and 19.53 g of octamethylcyclotetrasiloxane solution to 50 ° C through a heat exchanger, wherein lithium hexafluorophosphate and octamethylcyclotetrasiloxane The molar ratio of Si-O units of siloxane is 1:2.0.

[0076] (3) The ethyl methyl carbonate solution of the preheated lithium hexafluorophosphate and the octamethylcyclotetrasiloxane solution ente...

Embodiment 3

[0082] The reaction equation involved in embodiment 3 is as follows:

[0083] LiPF 6 +2(C 2 h 5 ) 3 -Si-O-Si-(C 2 h 5 ) 3 = LiPO 2 f 2 +4(C 2 h 5 ) 3 -Si-F↑

[0084] (1) Dissolve 10.00 g of lithium hexafluorophosphate in 90.00 g of diethyl carbonate dehydrated by 4A molecular sieves in a water bath at 10°C, stir for 0.5 h, and prepare a diethyl carbonate solution of lithium hexafluorophosphate with a mass fraction of 10%. Wherein, the moisture content in the diethyl carbonate detected by Metrohm 917 moisture tester is 35ppm.

[0085] (2) Use a peristaltic pump to preheat the diethyl carbonate solution of lithium hexafluorophosphate and 40.58 g of hexaethyldisiloxane solution respectively through a heat exchanger to 70° C., wherein lithium hexafluorophosphate and hexaethyldisiloxane The molar ratio of Si-O units of alkane is 1:2.5.

[0086] (3) the diethyl carbonate solution of lithium hexafluorophosphate after preheating and hexaethyldisiloxane solution enter in ...

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Abstract

The invention relates to the field of lithium ion secondary batteries, in particular to a method for preparing lithium difluorophosphate by a flow chemical method. The invention provides a method for preparing lithium difluorophosphate by a chemical flow method, which comprises the following steps of: respectively conveying a lithium hexafluorophosphate solution and siloxane into a pipeline of a micro-channel reactor to carry out continuous flow chemical reaction, and aging and separating the reaction liquid to take a solid phase, thereby obtaining lithium difluorophosphate. The purity of the prepared lithium difluorophosphate is 99.9% or above, and the content of lithium phosphate, the content of lithium metaphosphate and the content of lithium monofluorophosphate can be controlled to be 10 ppm or below. In the preparation process, air is isolated to control moisture, the micro-channel reaction is free of backmixing, the mass transfer effect is good, and sufficient reaction is ensured. Gas-liquid separation is carried out while aging reaction is carried out, so that the reaction efficiency is improved. The whole process is closed, siloxane and solvent closed-loop production is achieved, no obvious amplification effect exists, the production safety is high, and high-quality lithium difluorophosphate can be efficiently prepared with low cost.

Description

technical field [0001] The invention relates to the field of lithium ion secondary batteries, in particular to a method for preparing lithium difluorophosphate by a flow chemical method. Background technique [0002] Lithium difluorophosphate is an important functional additive in the electrolyte of lithium-ion secondary batteries, and is mainly used in the electrolyte of lithium-ion secondary batteries. Lithium difluorophosphate can form a stable electrolyte interface film on the surface of the positive electrode material and the negative electrode material, stabilize the electrode / electrolyte interface, inhibit the decomposition of the electrolyte, and reduce the interface impedance of the battery, thereby significantly improving the cycle stability of the battery at high and low temperatures performance and rate performance. By making lithium difluorophosphate form a film in the positive and negative electrodes, compared with conventional electrolyte batteries, the batte...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C01B25/455C01D3/02
CPCC01B25/455C01D3/02C01P2006/80
Inventor 岳敏张春晖左晏霖
Owner SHENZHEN YANYI NEW MATERIALS CO LTD
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