CN112456519A

CN112456519A - Method for recovering lithium hexafluorophosphate waste liquid

Info

Publication number: CN112456519A
Application number: CN202011384712.XA
Authority: CN
Inventors: 堀尾博英
Original assignee: Morita New Energy Materials Zhangjiagang Co ltd
Current assignee: Morita New Energy Materials Zhangjiagang Co ltd
Priority date: 2020-12-01
Filing date: 2020-12-01
Publication date: 2021-03-09

Abstract

The application discloses lithium hexafluorophosphate waste liquid recovery method adopts potassium salt and lithium hexafluorophosphate to react in the solvent, and the potassium hexafluorophosphate of formation is separated out through the mode of precipitation, and the lithium salt still dissolves in organic solvent, obtains pure potassium hexafluorophosphate after solid-liquid separation is dry, and liquid obtains the lithium salt after rotary drying, can collect organic solvent through the condensation in the rotary drying process also can carry out recycle. The method for recovering the lithium hexafluorophosphate waste liquid can obtain potassium hexafluorophosphate with the purity of more than 99.5 percent and pure lithium salt with the purity of more than 99 percent.

Description

Method for recovering lithium hexafluorophosphate waste liquid

Technical Field

The application relates to the field of waste liquid treatment of lithium hexafluorophosphate, in particular to a method for recovering lithium hexafluorophosphate analysis waste liquid.

Background

Lithium hexafluorophosphate is used as the electrolyte of the lithium ion battery, the quality of the important electrolyte salt of the electrolyte of the lithium ion battery has great influence on the overall performance of the lithium ion battery, and the content of insoluble impurities mainly containing lithium fluoride directly influences the quality of the lithium ion battery. The insoluble substances need to be analyzed and detected before the lithium hexafluorophosphate is used, and the mainstream detection and analysis method in the industry at present is to dissolve the lithium hexafluorophosphate by using an organic solvent, fully dissolve the lithium hexafluorophosphate and then carry out suction filtration to obtain the insoluble substances. In the detection process, the more lithium hexafluorophosphate is detected, the more organic waste liquid is used for analysis, and the organic solvents can only be entrusted to an external mechanism for incineration treatment in general, so that the organic solvents are wasted, and lithium hexafluorophosphate products in the solvents are wasted.

Because the existing analysis waste liquid can only be subjected to outsourcing treatment, the waste of the solvent and the lithium hexafluorophosphate is caused, the invention prepares the potassium hexafluorophosphate and other lithium salts by adding other potassium salts in the solvent to react with the lithium hexafluorophosphate, and collects the solvent in the drying process, thereby realizing the recycling of the analysis waste liquid.

Disclosure of Invention

The invention aims to provide a method for recovering lithium hexafluorophosphate waste liquid, which overcomes the defects in the prior art.

In order to achieve the purpose, the invention provides the following technical scheme: a method for recovering lithium hexafluorophosphate waste liquid is used for recovering lithium hexafluorophosphate analysis waste liquid, and comprises the following steps:

step 1: adding potassium salt into the lithium hexafluorophosphate analysis waste liquid, and fully stirring for reaction for 24-36 hours to obtain a mother liquid;

step 2: carrying out centrifugal separation on the mother liquor obtained in the step 1 to obtain a solid and a centrifugal liquid;

and step 3: drying the solid in the step 2 at the temperature of 80-100 ℃ for 2-4 hours to obtain potassium hexafluorophosphate solid;

and 4, step 4: carrying out rotary drying on the centrifugate in the step 2 at the temperature of 60-80 ℃, and drying at the temperature of 100-120 ℃ for 6-8 hours after the centrifugate is evaporated to dryness to obtain crude lithium bis (trifluoromethanesulfonimide);

and 5: and (3) dissolving the crude lithium salt in the step (4) by using pure water, filtering, and carrying out spray drying on the filtrate at the temperature of 110-130 ℃ to obtain pure lithium bistrifluoromethanesulfonylimide.

Preferably, in step 2, the solid is rinsed by adding a DMC solution during centrifugation.

Preferably, the potassium salt used in step 1 is 99.9% potassium bistrifluoromethanesulfonimide.

Preferably, the lithium salt in steps 3 and 4 is lithium bistrifluoromethanesulfonimide.

Compared with the prior art, potassium hexafluorophosphate with the purity of more than 99.5 percent and pure lithium salt with the purity of more than 99 percent can be obtained by reacting potassium salt with lithium hexafluorophosphate in a solvent.

Detailed Description

The technical solutions in the embodiments of the present invention will be described in detail below with reference to the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all embodiments. All other embodiments, which can be obtained by a person skilled in the art without any inventive step based on the embodiments of the present invention, are within the scope of the present invention.

Example one

Experiment raw materials: insoluble matter analysis waste liquid (DMC solution containing lithium hexafluorophosphate 85.5 g/L), 99.9% potassium bistrifluoromethanesulfonimide

The method comprises the following specific steps:

(1) 880g of potassium bis (trifluoromethanesulfonyl) imide is added into the 5L of analysis waste liquid, and the mixture is fully stirred and reacts for 36 hours;

(2) centrifuging the reaction mother liquor, adding 500ml of pure DMC during centrifugation, taking out the solid, and centrifuging the liquid for later use;

(3) the solid obtained by centrifugation was dried at 80 ℃ for 4 hours to obtain 458g of potassium hexafluorophosphate of which purity analysis result was 99.67%;

(4) rotary evaporating and drying the centrifugate at 60 ℃, drying for 8 hours at 100 ℃ after the centrifugate becomes solid to obtain crude bis (trifluoromethanesulfonimide) lithium, condensing and collecting 4.8L of solvent in the rotary evaporation process;

(5) the crude lithium bistrifluoromethylsulfonyl imide was fully dissolved in pure water and then filtered, and the filtrate was spray-dried at 120 ℃ to obtain 703g of lithium bistrifluoromethylsulfonyl imide, the purity of which was 99.46%.

Example two

Experiment raw materials: insoluble matter analysis waste liquid (DMC solution with lithium hexafluorophosphate content of 81 g/L), 99.9% potassium bis (trifluoromethanesulfonylimide)

The method comprises the following specific steps:

(6) adding 500g of potassium bis (trifluoromethanesulfonyl) imide into the 3L of analysis waste liquid, and fully stirring for reacting for 30 hours;

(7) centrifuging the reaction mother liquor, adding 500ml of pure DMC during centrifugation, taking out the solid, and centrifuging the liquid for later use;

(8) the solid obtained by centrifugation was dried at 90 ℃ for 3 hours to obtain 263g of potassium hexafluorophosphate of which purity analysis result was 99.52%;

(9) rotary evaporating and drying the centrifugate at 70 ℃, drying for 6 hours at 120 ℃ after the centrifugate becomes solid to obtain crude bis (trifluoromethanesulfonimide) lithium, condensing and collecting 2.9L of solvent in the rotary evaporation process;

(10) and fully dissolving the crude lithium bis (trifluoromethanesulfonyl) imide by using pure water, filtering, and carrying out spray drying on the filtrate at 110 ℃ to obtain 401g of lithium bis (trifluoromethanesulfonyl) imide, wherein the purity result is 99.54%.

To sum up, the method for recovering lithium hexafluorophosphate waste liquid of the present application obtains pure potassium hexafluorophosphate solid and pure lithium salt through the reaction of potassium salt and lithium hexafluorophosphate waste liquid.

It is noted that, herein, relational terms such as first and second, and the like may be used solely to distinguish one entity or action from another entity or action without necessarily requiring or implying any actual such relationship or order between such entities or actions. Also, the terms "comprises," "comprising," or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, article, or apparatus. Without further limitation, an element defined by the phrase "comprising an … …" does not exclude the presence of other identical elements in a process, method, article, or apparatus that comprises the element.

The foregoing is merely a detailed description of the present application, and it should be noted that modifications and embellishments could be made by those skilled in the art without departing from the principle of the present application, and these should also be considered as the protection scope of the present application.

Claims

1. A method for recovering lithium hexafluorophosphate waste liquid is used for recovering lithium hexafluorophosphate analysis waste liquid, and is characterized in that: the method comprises the following steps:

and 4, step 4: carrying out rotary drying on the centrifugate in the step 2 at 60-80 ℃, and drying at 100-120 ℃ for 6-8 hours after the centrifugate is evaporated to dryness to obtain a crude lithium salt;

and 5: and (3) dissolving the crude lithium salt in the step (4) by using pure water, filtering, and carrying out spray drying on the filtrate at the temperature of 110-130 ℃ to obtain the pure lithium salt.

2. The method for recovering lithium hexafluorophosphate waste liquid according to claim 1, characterized in that:

in step 2, the solid is rinsed by adding a DMC solution during centrifugation.

3. The method for recovering lithium hexafluorophosphate waste liquid according to claim 1, characterized in that: the potassium salt used in the step 1 is 99.9% potassium bistrifluoromethanesulfonimide.

4. The method for recovering the lithium hexafluorophosphate waste liquid according to claim 3, characterized in that: the lithium salt in the steps 3 and 4 is bis (trifluoromethanesulfonimide) lithium.