CN102323175A - Method for testing content of lithium hexafluorophosphate in electrolyte of lithium ion battery - Google Patents

Abstract

The invention discloses a method for measuring the content of lithium hexafluorophosphate in electrolyte of a lithium ion battery, which comprises the following steps of: diluting a certain mount of electrolyte into 100ml of water; adding an acidic reagent; heating to hydrolyze PF6- into PO43- under the heating condition; after cooling, adding a quinoline, sodium molybdate, citric acid and acetone reagent; under the slight boiling condition, performing a reaction to generate yellow phosphomolybdic acid quinoline precipitates; and by filtering, washing, drying and weighing the precipitates, calculating the content of the lithium hexafluorophosphate according to the weight of the precipitates.

Description

The method of testing of hexafluorophosphoric acid lithium content in the lithium-ion battery electrolytes

Technical field

The present invention relates to lithium ion battery and make the field, is hexafluorophosphoric acid Measurement of lithium content in the lithium-ion battery electrolytes specifically.

Background technology

Topmost electrolyte is a lithium hexafluoro phosphate in the lithium-ion battery electrolytes, and its concentration directly has influence on the electric conductivity of electrolytic solution, and price own is very expensive, and the content of therefore accurately measuring lithium hexafluoro phosphate in the lithium-ion battery electrolytes is very important.

Hexafluorophosphoric acid Measurement of lithium content method has the atomic absorption spectrophotometry and the IC chromatography of ions in present disclosed electrolytic solution.Atomic absorption spectrophotometry adopts the lithium ion assay method, and when containing two kinds and above lithium-ion electrolyte in the electrolytic solution, the method can't determine the content of lithium hexafluoro phosphate.And the IC chromatography of ions rarely adopts so far, and its pre-treatment required time is longer, and testing conditions is had relatively high expectations, and process is complicated, and is difficult to popularize.

Summary of the invention

The objective of the invention is to find a kind of easy, quick, accurate, and cost is lower, the hexafluorophosphoric acid Measurement of lithium content method that is easy to promote.

The present invention is through (7～10%HNO in acid solution ₃), PF ₆ ^-Be heated and be hydrolyzed to PO ₄ ^3-And HF, reaction equation is following:

PO ₄ ^3-With sodium molybdate and quinoline effect, form phosphomolybdic acid quinoline deposition, reaction equation is following:

H ₃PO ₄+3C ₉H ₇N+12Na ₂MoO ₄+24HNO ₃→

(C ₉H ₇N) ₃H ₃[PO ₄·12MoO ₃]·H ₂O↓+11H ₂O+24NaNO ₃

Said step is following:

It is soluble in water to take by weighing a certain amount of electrolytic solution, adds a certain proportion of acid reagent, heats little about 30min that boils; It is taken down the cooling back add the quinoline molybdenum lemon ketone reagent for preparing, little boiling to precipitated and separated taken off; Filter with glass core crucible the cooling back, dry, constant weight in thermostatic drying chamber.

Said acid reagent can be any one in hydrochloric acid, nitric acid, sulfuric acid, the perchloric acid, more preferably nitric acid.

The preferred G4 model of said glass core crucible.

Said baking temperature can carry out under 150-180 ℃, preferred 180 ℃ of this method.

The practical implementation method:

(1) preparation quinoline molybdenum lemon ketone reagent:

A:70 gram sodium molybdate is dissolved in the 100ml water;

B:60 gram citric acid is dissolved in the 150ml water, adds 85ml nitric acid;

C: stir down, add A among the B mixing;

D:35ml nitric acid adds in the 100ml water, adds the 5ml quinoline again;

E: D is added among the C, behind the mixing, placed 24 hours, filter, add 280ml third in the filtrating

Ketone is diluted with water to 1000ml, is stored in the polyethylene bottle.

(2) measure formality:

It is soluble in water to take by weighing 0.10-0.20 gram (being accurate to 0.0001g) electrolytic solution, and above-mentioned test solution is moved in the 250ml beaker, adds the 10ml1+1 salpeter solution, is diluted to 100ml; The cover upper surface ware places little boiling 30 minutes on the electric furnace, takes off, and is diluted with water to 100ml; Add 35ml quinoline molybdenum lemon ketone reagent, cover upper surface ware, little boiling on electric furnace to precipitated and separated (about 10 minutes); Take off, be chilled to room temperature, cooling procedure is rotated beaker 3～4 times.

G4 glass core crucible with (45min) is dried to constant weight under 180 ℃ in advance filters, and washing precipitation 6-8 time is dried to constant weight under 180 ℃.

Do blank simultaneously.

(3) calculate the hexafluorophosphoric acid lithium content in the electrolytic solution to be measured according to following formula:

${\mathrm{LiPF}}_6\%=\frac{G_2-G_1}{W*0.2039}\×0.014\×100$

In the formula:

G ₂-deposition adds the weight of crucible, g,

G ₁The weight of-crucible, g,

The W-sample weighting amount, g,

0.014-reduction coefficient,

0.2039-P be scaled LiPF ₆Coefficient.

(4) test result sees the following form:

Visible by The above results, measure the error requirements that hexafluorophosphoric acid lithium content in the lithium-ion battery electrolytes can satisfy absolute error ± 0.5% with method of the present invention, precision is higher.

From the method narration, can find out; Used reagent of method of the present invention and equipment are comparatively common and cheap, nontoxic, and method operation itself is simple relatively, easy to operate; Test duration is shorter relatively, can be described as one simply, fast, method of testing accurately.

Claims (3)

1. hexafluorophosphoric acid Measurement of lithium content method in the lithium-ion battery electrolytes is characterized in that:

It is soluble in water to take by weighing a small amount of electrolytic solution, and in solution, adds a certain amount of salpeter solution, makes solution be acid, in heating process, makes PF ₆ ^-Be heated and be hydrolyzed to PO ₄ ^3-

Contained PF in solution ₆ ^-Fully after the hydrolysis, add quinoline molybdenum lemon ketone reagent, PO ₄ ^3-With sodium molybdate and quinoline effect, form phosphomolybdic acid quinoline deposition, deposition is leached also dry the weighing weight of precipitate after the washes clean.

2. the salpeter solution in said 1.1 can be any one of hydrochloric acid, nitric acid, sulfuric acid, perchloric acid.

3. the precipitation agent in said 1.2 is a quinoline molybdenum lemon ketone reagent.