Method for preparing lithium oxalyldifluoroborate

Abstract

The invention discloses a method for preparing lithium oxalyldifluoroborate. According to the method, first, a boracic compound reacts with potassium oxalate (rubidium or cesium) to form difluoro oxalic acid potassium borate (rubidium or cesium) through synthesis; then, a difluoro oxalic acid potassium borate (rubidium or cesium) water solution slowly flows through superacidulated cationic resin for exchange, and an appropriate amount of Li2CO3 or LiOH is added into a collected difluoro oxalic acid boric acid water solution for the neutral reaction to obtain a crude lithium oxalyldifluoroborate product; high-purify lithium oxalyldifluoroborate is obtained through recrystallization purification. The method has the advantages that operation steps are simple, preparation conditions are moderate, cost is low, ionic impurities can be effectively controlled, and the method is suitable for industrialized mass production.

Description

technical field [0001] The invention belongs to the technical field of manufacture of lithium (ion) battery electrolyte materials, in particular to lithium difluorooxalate borate (Li[B(C 2 o 4 ) F 2 ], the preparation of LiDFOB). technical background [0002] Due to LiPF 6 The chemical stability is poor, the temperature is above 55 ℃ or LiPF 6 When in contact with protic solvents (such as water, alcohols, etc.), it will decompose significantly, and the resulting phosphorus pentafluoride (PF 5 ), phosphorus oxyfluoride (OPF 3 ) and hydrogen fluoride (HF) and other impurities are fatal to the electrolyte and electrode materials, which is an important reason for the shortened service life of batteries and the root cause of battery safety problems (C.L.Campion, et al, J.Electrochem . Soc., 2005, 152, A2327; H. Yang, et al, J. Power Sources, 2006, 161, 573). Therefore, the development of conductive lithium salts with superior chemical and electrochemical stability has been...

AI Technical Summary

Problems solved by technology

The purity of the product obtained by this method is greatly improved, but due to the introduction of Cl in the reaction process - Ionic impurities while using LiBF 4 Raw materials, resulting in higher preparation costs

3) In DMC solvent, by BF 3 ·O(CH 2 CH 3 ) 2 and Li 2 C 2 o 4 Reaction to prepare LiDFOB, and use DMC as a solvent to purify by recrystallization (S. Zhang, Electrochem. Commun., 2006, 8, 1423), but the reaction time is longer, and the target product has greater solubility in DMC , so the crystallization time is slow, the yield is low, and the product is still easily mixed with LiBF 4 by-product

4) Schreiner et al. in acetonitrile solvent, by LiBF 4 and (CH 3 ) 3 SiOCOCOOSi (CH 3 ) 3 React at 40-50°C for 1 day, the yield is as high as 97%, but the disadvantage is that the reaction time is longer, and LiBF is used at the same time 4 As a raw material, the production cost has been increased (C.Schreiner, et al, Chem.Eur.J., 2009,15,2270)

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