GB/T 45330-2025 Cathode materials for lithium ion batteries - Determination of water content - Carl fisher coulomb method
1 Scope
This document describes the method for determining the water content in cathode materials for lithium ion batteries using the Carl fisher coulomb method.
This document is applicable to the determination of water content in cathode materials such as LITHIUM COBALT OXIDE (LCO), Lithium Nickel Cobalt Manganese Oxide (NCM), Lithium Nickel Cobalt Aluminum Oxide (NCA), Lithium Manganese Oxide (LMO), Lithium Iron Phosphate (LFP), and Lithium Manganese Iron Phosphate (LMFP), with a determination range of 0.0005% to 0.5000%.
2 Normative references
The following documents contain requirements which, through reference in this text, constitute provisions 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 8170 Rules of rounding off for numerical values & expression and judgment of limiting values
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
3.1
dew point temperature
temperature at which the vapor pressure of water in a gas is equal to the saturation vapor pressure of water at that temperature
4 Principle
The sample is heated in a furnace, where the water in the sample evaporates into water vapor and is carried by a dried carrier gas into the titration cup of the Carl Fisher moisture meter for determination. The water in the sample undergoes a chemical reaction with iodine and sulfur dioxide in a low-alcohol solution (such as methanol) and an organic base (RN). The electrolytic cell continuously electrolyzes iodide ions () to produce iodine (I₂), which reacts with the water in the sample. The reaction equation is as follows:
H₂O + I₂ + SO₂ + CH₃OH + 3RN → [RHN]SO₄CH₃ + 2[RHN]I
Titration is performed according to the above reaction equation until all the water has reacted completely. According to Faraday's Law, the amount of substance of iodine produced is directly proportional to the amount of electricity consumed. The water content in the sample is calculated by determining the amount of electricity required to convert into I₂.
Contents
1 Scope
2 Normative references
3 Terms and definitions
4 Principle
5 Reagents or materials
6 Instruments and equipment
7 Samples
8 Test conditions
9 Test procedure
10 Test data processing
11 Precision
12 Test report
Annex A (Informative) Original data of precision test
