Synthesis technique for obtaining difluoro oxalate lithium borate and di-oxalate lithium borate

Abstract

The invention discloses a synthesis technique for simultaneously obtaining difluoro oxalate lithium borate and di-oxalate lithium borate with outstanding performances, comprising the following steps:1. reacting fluorinated compound, boracic compound, lithium-containing compound and oxalate-containing compound in a reaction medium at 100 DEG C with reaction pressure of 0.1-1MPa, wherein the mol ratio of lithium, fluorine, boron and oxalate ions is 5-9:5-9:-2-3:3-4, and generating a reaction solution containing difluoro oxalate lithium borate and di-oxalate lithium borate; 2. carrying out initial separation on the difluoro oxalate lithium borate and di-oxalate lithium borate in the reaction solution, then carrying out further extraction separation by using organic solvent capable of extracting difluoro oxalate lithium borate or di-oxalate lithium borate; and 3. respectively carrying out recrystallization and vacuum drying to obtain the difluoro oxalate lithium borate and di-oxalate lithium borate of battery level. The invention is suitable for industrially producing two types of lithium salts with excellent performance used for lithium ion batteries.

Description

technical field [0001] The invention relates to the technical field of preparation of electrolyte salts used in lithium ion batteries, in particular to a synthesis process capable of simultaneously obtaining lithium difluorooxalate borate and lithium bisoxalate borate. Background technique [0002] As the main component of lithium-ion batteries, electrolyte has always been one of the research focuses in this technical field. LiPF currently in commercial large-scale application 6 Insufficient thermal stability, easy to decompose into LiF and PF 5 , the latter is readily hydrolyzed to form HF and PF 3 O. These two hydrolysis products have high reactivity for both positive and negative electrodes, and they inevitably exist in LiPF 6 have a detrimental effect on the performance of the electrode. LiAsF 6 Due to its high toxicity due to its arsenic content, large-scale use is not advocated. LiClO 4 It is a strong oxidant, easy to explode, and poor in safety. LiBF 4 Poor ...

AI Technical Summary

Problems solved by technology

The aqueous phase synthesis is LiBOB synthesized in water with lithium hydroxide, oxalic acid, and boric acid. This method involves high temperature and oxalic acid aqueous solution requires extremely high equipment; 3 ) 3 with (CH 3 ) 3 SiOOCCOOSi (CH 3 ) 3 Synthetic, but the raw material price of this method is expensive and not suitable for industrial production; the solid-phase method is synthesized with lithium hydroxide, oxalic acid, and boric acid after being evenly ground and generated at a high temperature. This method requires high equipment requirements as the water-phase method.

[0010] Lithium difluorooxalate borate (LiODFB) was developed late and not much research

In European Patent No., the following method is disclosed in the document of EP1308449A2: react in dimethyl carbonate with oxalic acid, lithium tetrafluoroborate and aluminum chloride or silicon tetrachloride or react with oxalic acid, lithium tetrafluoroborate, lithium fluoride and The reaction of boron trichloride or trimethoxyboron in dimethyl carbonate realizes the synthesis of LiODFB, but HCl is generated in the reaction of this method, and the reaction is violent, and the high requirements for equipment are not conducive to industrial production.

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