Preparation method of lithium difluoro(bisoxalate)phosphate

Abstract

The invention provides a preparation method of lithium difluoro(bisoxalate)phosphate. Lithium difluoro(bisoxalate)phosphate is prepared by a reaction between phosphorus pentafluoride and lithium oxalate. The preparation method comprises the following steps: 1) adding anhydrous lithium oxalate into a high pressure reactor with a stirrer, sealing, and vacuum-pumping; 2) slowly introducing phosphoruspentafluoride gas and high-purity carbon dioxide into the reactor at a low temperature; 3) slowly heating to 70 DEG C, adjusting pressure of the reactor to an appropriate value, and continuously stirring and reacting; and 4) carrying out separation and purification after the reaction. According to the method, raw materials are cheap and easily-available, and the reaction is carried out under mildconditions. The reaction steps are simple, and operation is convenient; the target product is only lithium difluoro(bisoxalate)phosphate; the product has high yield and high purity, and is easy to purify; the reaction is fast, postprocessing is simple, and feasibility of the industrial production is increased.

Description

technical field [0001] The invention belongs to the technical field of electrolytes, and in particular relates to a preparation method of lithium difluorobisoxalate phosphate. Background technique [0002] In recent years, due to the rapid development of smart devices such as mobile phones and tablet computers, the market share of small lithium batteries has grown rapidly. In addition, the technology of electric vehicles is becoming more and more perfect, and the market demand for large lithium batteries is also gradually released. It is expected that lithium batteries will maintain a growth trend in the next few years . Lithium batteries are mostly secondary batteries, and their poor high-voltage workability, cycle and rate performance are the difficulties that hinder their development. Lithium difluorobisoxalate phosphate (LiDFBP), as a new type of lithium salt additive, can exhibit excellent cycle performance and rate performance when applied to lithium-rich cathode mate...

AI Technical Summary

Problems solved by technology

For example, CN102216311, WO2013180174, WO2014097772, and JP2016201244 all use lithium hexafluorophosphate and oxalic acid, and add silicon tetrachloride; the high chlorine compounds and free acids in the solution hinder its further application in lithium-ion battery electrolyte; WO2016002771 uses dichlorotetrafluorophosphoric acid Lithium reacts with oxalic acid, but lithium dichlorotetrafluorophosphate needs to be synthesized, which increases the reaction steps and is not conducive to industrial production; the preparation method of lithium difluorobisoxalate phosphate in WO2016052092 and WO2016117279 uses HF, which is strongly irritating to the skin and Corrosive, not conducive to industrial production; KR1020130102969 uses lithium hexafluorophosphate to react with bis(trialkylsilyl) oxalate, wherein bis(trialkylsilyl) oxalate also reacts with Si-containing compounds through oxalic acid, which increases the reaction step; and lithium hexafluorophosphate is easy to absorb water, the price is high, it is not easy to store, and it is not conducive to industrial production