Preparation method of alkali metal salt of bis(fluorosulfonyl)amide

Abstract

The invention discloses a preparation method of alkali metal salt of bis(fluorosulfonyl)amide. The preparation method comprises the step of carrying out fluoridation on alkali metal salt of bis(chlorosulfonyl)amide in an polar aprotic solvent by taking ion liquid as a phase transfer catalyst and alkali metal fluoride as a fluorinating agent, so as to obtain corresponding alkali metal salt of bis(fluorosulfonyl)amide. Compared with the prior art, the preparation method has the advantages that reaction conditions are mild, the yield and the purity are high, the product is easily separated and purified, the ion liquid catalyst can be recycled and reduced, and the like. The preparation method is applicable to industrial mass production.

Description

technical field [0001] The invention belongs to the synthesis of fluorine-containing ion compounds by fluorine-chlorine exchange, and the alkali metal salt (M[N(SO 2 f) 2 ], referred to as M[FSI], M=Li, Na, K, Rb, Cs). Background technique [0002] In recent years, the alkali metal salt of bisfluorosulfonimide (M[N(SO 2 f) 2 ], referred to as MFSI) (formula (I)) as a conductive salt material for electrolytes, has been widely used in the fields of lithium-ion batteries, sodium-ion batteries, and potassium-ion batteries (Journal of Fluorine Chemistry, 2015 174, 49–61; Electrochemistry Communications 2015, 60, 172–175;). For example, lithium bisfluorosulfonyl imide (LiFSI) is used as the traditional lithium salt lithium hexafluorophosphate (LiPF 6 ) additives, which can improve the cycle performance of the ternary material nickel-cobalt-manganese (NCM) lithium-ion battery (Journal of The Electrochemical Society 2015, 162 (1) A169-A175); lithium bisfluorosulfonyl imide (LiF...

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Problems solved by technology

These preparation methods have the following obvious disadvantages: (1) AsF 3、 HF and KHF 2 (or NH 4 HF 2 ) are highly toxic reagents, and the practical application value of the reaction method is limited; (2) SbF 3 As a fluorinating agent (Inorg.Chem.1998,37,6295), not only the cost is high, but also the by-product SbCl produced by the reaction 3 Easy to sublime, distilled out together with the product HFSI, difficult to separate, resulting in difficulty in separation and purification; (3) BiF 3 Solvent-free fluorination homogeneous fluorination (US8377406), also produces highly toxic HF; (4) ZnF 2 It is a fluorinating agent (US8134027), and in the aftertreatment of fluorination, a large amount of ammonia and Zn 2+ reaction, by generating Zn(NH 3 ) 4 2+ Removal of metal zinc ions causes a large amount of waste water to be produced; (5) KF is used as a single fluorinating agent to carry out fluorination in an organic solvent. Because it is heterogeneous fluorination, the reaction speed is slow, the fluorination efficiency is low, and the reaction There are also a large number of highly toxic HF by-products generated

There are two obvious deficiencies in the chemical principle of this method: (1) due to the oxygen atom of the catalyst crown ether and Li + It has a strong coordination ability, and it forms a complex. The crown ether is extremely difficult to remove by conventional methods (such as heating under reduced pressure), and it is difficult to obtain high-purity lithium bisfluorosulfonyl imide (LiFSI) (such as LiFSI's analog double three Lithium fluoromethylimide (LiTFSI) forms very stable complexes with substances containing four or more ether functional groups, Chem.Lett.2010,39,753-755); (2) crown ether and fluorinating agent The complex formed by the fluoride (MF) of the alkali metal salt ([crown ether-M + ]F - ) the metal ion M of the fluorinating agent MF (M=Na, K, Rb, Cs) + Bring into the organic phase containing the raw material LiClSI, after fluorination, get mixed with metal ions M + (M=Na, K, Rb, Cs) LiFSI

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