Preparation method of lithium bis (oxalato) borate

Abstract

The invention discloses a preparation method of lithium bis (oxalato) borate, which comprises the following steps: in the presence of aprotic organic amine, oxalic acid reacts with the aprotic organic amine to generate an organic amine oxalic acid complex, and the aprotic organic amine is excessive relative to the oxalic acid; reacting the organic amine oxalic acid complex with a boron source to generate an organic amine oxalic acid boron source complex, and removing moisture generated in the reaction process; then mixing and reacting the organic amine boron oxalate source complex with a lithiated compound to generate lithium bis (oxalato) borate; the method has the advantages of being simple to operate, easy to realize safely, low in equipment requirement and the like on the basis of obtaining ideal yield, the crude product yield of the prepared lithium bis (oxalato) borate can reach 95% or above, and when the purity of the lithium bis (oxalato) borate is increased to 99.95% or above, the yield can still reach 85% or above.

Description

technical field [0001] The invention belongs to the technical field of preparation of lithium ion electrolytes, and in particular relates to a preparation method of lithium bis-oxalate borate. Background technique [0002] Lithium bis(oxalate)borate, Lithium bis(oxalate)borate, is a new type of lithium salt electrolyte with good electrochemical stability and thermal stability, and the electrolyte containing Lithium bis(oxalate)borate can form stable and dense on the anode. SEI film, with excellent multi-cycle performance, has higher thermal stability and safety compared with lithium hexafluorophosphate. [0003] At present, the preparation methods of lithium bis-oxalate borate mainly include liquid phase method and solid phase method; [0004] For example, the following liquid phase method: this method contains lithium source compounds, boron source compounds and oxalate compounds in a molar ratio of 1:1:2, using water, toluene, tetrahydrofuran or acetonitrile as a solvent,...

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Problems solved by technology

[0004] For example, the following liquid phase method: the method contains lithium source compound, boron source compound and oxalate compound according to the molar ratio of 1:1:2, with water, toluene, tetrahydrofuran or acetonitrile as solvent, 0.15-8 MPa in a closed tank Heating and reacting under pressure, the obtained solution was distilled under reduced pressure and vacuum dried to obtain lithium bisoxalate borate with a yield of more than 99%. The specific purity is not specified, but the operation under pressure has certain unsafe risks, and the potential safety hazard is relatively large. At the same time Since the raw materials such as boron source compounds and oxalate compounds are basically acidic, they are highly corrosive to equipment and have high requirements for process equipment, which greatly increases production costs;

[0005] The solid-phase method currently reported is the solid-phase synthesis of lithium bisoxalate borate by ball milling method, or the solid-phase synthesis of lithium bisoxalate borate by microwave method, but basically there is the problem of uneven mixing, which leads to insufficient reaction and by-product impurities Many, low yield and low purity

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