SJ/T 11794-2022 English PDF (SJT11794-2022)

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SJ/T 11794-2022: Test method for unbonded lithium of cathode materials used in lithium ion battery
SJ/T 11794-2022
SJ
ELECTRONIC INDUSTRY STANDARD
OF THE PEOPLE'S REPUBLIC OF CHINA
ICS 31.030
CCS L 90
SJ/T 11794-2022
Test method for unbonded lithium of cathode materials used
in lithium ion battery
ISSUED ON: MARCH 24, 2022
IMPLEMENTED ON: JULY 01, 2022
Issued by: Ministry of Industry and Information Technology of the People’s
Republic of China.
Table of Contents
Foreword ... 3
1 Scope ... 4
2 Normative references ... 4
3 Terms and definitions ... 4
4 Principle of the method ... 5
5 Instruments, equipment, and materials ... 5
6 Sample processing and determination ... 6
7 Calculation of results ... 6
8 Test report ... 8
Test method for unbonded lithium of cathode materials used
in lithium ion battery
1 Scope
This document specifies the test method for the content of unbonded lithium of cathode
materials used in lithium ion batteries.
This document applies to the determination of the content of unbonded lithium in
cathode materials such as lithium nickel cobalt manganate, lithium nickel cobalt
aluminate, lithium cobalt oxide, lithium manganate, lithium nickel manganate, and
lithium-rich manganese base. The determination of the content of unbonded lithium in
other cathode materials can also refer to this document.
2 Normative references
The following referenced documents are indispensable for the application of this
document. For dated references, only the edition cited applies. For undated references,
the latest edition of the referenced document (including any amendments) applies.
GB/T 6682 Water for analytical laboratory use - Specification and test methods
3 Terms and definitions
For the purpose of this document, the following terms and definitions apply.
3.1
residual alkali
Lithium hydroxide and lithium carbonate attached to the surface of cathode materials.
3.2
unbonded lithium
Lithium in residual alkali.
4 Principle of the method
Dissolve lithium carbonate and lithium hydroxide in the sample in distilled water, and
then filter. When using dilute hydrochloric acid solution as the titration solution to
perform automatic potentiometric titration on the filtrate, the following reactions will
occur:
LiOH + HCl = LiCl + H2O
Li2CO3 + HCl = LiHCO3 + LiCl
With the continuous addition of dilute hydrochloric acid solution, all lithium hydroxide
will be converted into lithium chloride and water, and all lithium carbonate will be
converted into lithium bicarbonate and lithium chloride. At this time, the pH value is
about 8.0 ~ 9.0, and an electrode potential jump point EP1 will appear on the automatic
potentiometric titrator. The dilute hydrochloric acid solution is continued to be added
dropwise, the following reaction will occur:
LiHCO3 + HCl = LiCl + CO2↑ + H2O
Lithium bicarbonate will all be converted into lithium chloride, carbon dioxide, and
water. At this time, the pH value is about 4.0 ~ 5.0, and another electrode potential jump
point EP2 will appear on the automatic potentiometric titrator. By recording the
consumption of dilute hydrochloric acid corresponding to the potential jump points EP1
and EP2, the contents of lithium carbonate and lithium hydroxide in the sample can be
calculated, and then the total content of unbonded lithium can be calculated based on
the mass fraction of lithium in lithium carbonate and lithium hydroxide.
5 Instruments, equipment, and materials
5.1 Automatic potentiometric titrator. The titration accuracy is not less than 20 μL.
5.2 Magnetic stirrer. The rotation speed is adjustable from 0 r/min to 1000 r/min.
5.3 Balance. The accuracy is not less than 0.0001 g.
5.4 Distilled water. Distilled water is obtained by heating, boiling, and cooling the grade
3 water that meets the requirements of GB/T 6682. Distilled water shall be covered and
stored for later use. The validity period is 72 h.
5.5 Hydrochloric acid standard solution. 0.1 mol/L or 0.5 mol/L or l mol/L.
5.6 Hydrochloric acid titration solution. According to the estimated content of
unbonded lithium in the sample, select a hydrochloric acid standard solution of
appropriate concentration. Use a pipette to accurately transfer an appropriate amount of
the hydrochloric acid standard solution into a volumetric flask, add distilled water to