Preparation method of lithium hexafluorophosphate

Abstract

The invention discloses a preparation method of lithium hexafluorophosphate. The preparation method comprises the following steps: (1) introducing phosphorus pentafluoride gas into a reaction kettle filled with lithium fluoride and hydrogen fluoride liquid and carrying out reaction for 1 to 2 hours to obtain a lithium hexafluorophosphate solution; (2) realizing partial crystallisation under a stirring condition; (3) carrying out drying. The preparation method of lithium hexafluorophosphate disclosed by the invention has the advantages that the operation is convenient, the lithium hexafluorophosphate which is obtained by carrying out partial crystallisation is directly formed into uniform particles, so that the steps of multiple drying and pulverization are eliminated, and the partial crystallisation time is shortened.

Description

technical field [0001] The present application relates to the technical field of lithium ion batteries, in particular to a method for preparing lithium hexafluorophosphate. Background technique [0002] Lithium-ion batteries have outstanding advantages such as high working voltage, high energy density (light weight), low self-discharge rate, no memory effect, long cycle life and no pollution. In recent years, it has quickly occupied many fields with its incomparable advantages over other batteries, and is widely used in well-known mobile phones, notebook computers, small cameras, electric vehicles and other products. With the industrialization of electric vehicles, the amount of lithium-ion batteries is bound to increase. The application shows that lithium-ion battery is an ideal small green power source. [0003] Lithium hexafluorophosphate is an important electrolyte salt of lithium-ion battery electrolyte, which requires high purity (usually not less than 99.5%), and im...

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Problems solved by technology

[0003] As an important electrolyte salt of lithium ion battery electrolyte, lithium hexafluorophosphate requires high purity (usually not less than 99.5%), and impurities such as water, alkali metals, heavy metals and other impurities such as PCl 3 and POCl 3 The content must be strictly controlled, otherwise it will lead to increased internal resistance of the battery, rapid decay of battery capacity, shortened cycle life, and even affect the safety of the battery

[0010] (1), the first-level drying in step 4 is standing and drying, and the crystallization time generally takes about 48 hours, and it is easy to agglomerate. After crystallization, the lithium hexafluorophosphate product forms a larger crystal block as a whole, and it is difficult to remove from the crystallization tank. It is difficult to peel off and break in the middle. After the primary drying, the lithium hexafluorophosphate product needs to be crushed according to the particle size requirements, which is time-consuming and laborious. The product particles obtained by the prior art are as follows: figure 1 As shown, its shape is irregular and its surface is rough;

[0011] (2) Only a small amount of reaction raw materials can be processed each time, which cannot meet the production needs of large quantities

[0012] (3) It needs to be dried twice, which takes a long time and consumes time and energy.

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