YS/T 1028.4-2015 in English
VALIDMethods for chemical analysis of lithium iron phosphate―Part 4:Determination of carbon content―High frequency combustion with infrared absorption method
- Issued on:2015-04-30
- Implemented on:2015-10-01
- File Format:PDF
- Delivery:Via email within 1~3 business days
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本部分规定了磷酸铁锂中碳量的测定方法。本部分适用于磷酸铁锂中碳含量的测定。测定范围：0.5%～5.0%。
Introduction
Technical background of the standard
This part, as the 4th unit of the YS/T1028 series of standards, establishes a standardized detection method for the key impurity element carbon in the positive electrode material lithium iron phosphate of lithium-ion batteries. With the explosive growth of the power battery industry after 2010, higher requirements have been put forward for material purity control, and traditional chemical analysis methods can no longer meet the needs of the industry.
Analysis of the principle of the method
Based on the spectral absorption principle of the Beer-Lambert law, the carbon element in the sample is converted into CO2 gas through a high-frequency induction furnace (working temperature ≥1200℃), and the characteristic absorption peak intensity is measured by an infrared detector. The key technical parameters include:
| Parameter | Requirement | Function |
|---|---|---|
| Oxygen purity | ≥99.5% | Ensure complete combustion |
| Flux ratio | Pure iron: tungsten particles = 1:5.7 | Lower melting temperature |
| Sample particle size | ≤0.10mm | Ensure reaction uniformity |
Key operating specifications
6.1 Sample processing
It needs to be sealed and stored after drying at 110±5℃ for 1 hour. The typical sample weight is 0.20g (accuracy 0.1mg). Actual cases show that exceeding the particle size standard can lead to a deviation of the measurement result of up to 12%.
6.5 Determination process
- Pretreatment of porcelain crucible: calcination at 1200℃ for 2 hours
- Sample stacking order: pure iron base→sample→tungsten grain covering
- Burn time control: usually 40-60 seconds
Quality control requirements
| Carbon content range (%) | Repeatability limit r (%) | Tolerance (%) |
|---|---|---|
| 0.5-1.7 | 0.01-0.03 | 0.05 |
| 3.5-5.0 | 0.11 | 0.20 |
Note: Blank calibration (pure iron + tungsten particle combination) and standard material verification (NIST series standard samples) should be performed for each batch.
Implementation suggestions
Key points for instrument selection
- The resolution of the infrared detector should be ≤0.001%
- Equipped with a multi-stage gas purification system (containing caustic soda asbestos + magnesium perchlorate)
- It is recommended to use an automatic sampling system to reduce human errors
Abnormal handling plan
When the measured value exceeds the allowable difference, check: porcelain crucible contamination, oxygen flow stability (recommended 1.5L/min), and flux batch consistency.
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