Determination of 14 Impurity Elements in Lithium Carbonate Using ICP-OES

Significance of the Topic

The rapid expansion of lithium-ion battery technology in consumer electronics and electric vehicles has heightened the need for reliable quality control of cathode raw materials. Lithium carbonate purity directly impacts battery performance, safety, and lifetime. Accurate determination of trace elemental impurities in battery-grade Li2CO3 is therefore critical for suppliers and manufacturers striving for consistent high performance and regulatory compliance.

Objectives and Study Overview

This study aimed to develop a streamlined, single-run method for quantifying 14 impurity elements (Al, Ca, Cd, Cu, Fe, K, Mg, Mn, Na, Ni, Pb, S, Si, Zn) in lithium carbonate using inductively coupled plasma optical emission spectrometry (ICP-OES) with standard addition calibration. The goals were to simplify analysis by including silicon, improve accuracy for easily ionized elements, and demonstrate method stability and throughput for routine quality control.

Methodology and Instrumentation

Sample Preparation and Calibration

• Approximately 0.3 g of solid Li2CO3 was digested in concentrated HNO3 on a hotplate at 120 °C for 2 h, then diluted to 30 mL.
• Matrix-matched calibration standards for 14 elements were prepared by standard addition to account for matrix effects.

Instrumentation

• Agilent 5110 Vertical Dual View (VDV) ICP-OES with cooled cone interface to reduce easily ionized element interferences.
• SeaSpray concentric glass nebulizer, double-pass cyclonic spray chamber, and demountable torch.
• VistaChip III CCD detector for rapid full-spectrum acquisition, enabling 60 s run time per sample.
• Axial viewing for Na and K to minimize spectral interferences while maintaining sensitivity for trace analytes.

Background Correction

• Automatic Fitted Background Correction (FBC) in ICP Expert software was used to model and subtract overlapping emission structures without manual intervention.

Key Results and Discussion

Method Detection Limits

• All 14 elements achieved detection limits below 1 µg/L in solution, corresponding to sub-mg/kg levels in Li2CO3.

Calibration and Linearity

• Standard addition produced linear calibration curves (R² > 0.9995) for all elements across 0.005–0.1 mg/L ranges.

Accuracy and Precision

• Spike-recovery tests at 50 µg/L yielded recoveries of 95–102% for all targets, confirming method accuracy.
• Long-term stability over 2.5 h (n=150 injections) showed relative standard deviations below 2% for all elements.

Benefits and Practical Applications

This approach consolidates the measurement of major and trace impurities, including silicon, into a single ICP-OES analysis. The rapid 60 s analysis time and low argon consumption improve laboratory throughput and reduce operating costs. Robust accuracy and stability enable reliable routine quality control of lithium carbonate for battery manufacturing.

Future Trends and Opportunities

Advances in high-resolution detectors and software-driven background correction will further enhance sensitivity and reduce spectral overlap. Integration of automated sample preparation and robotics may support higher throughput in battery material screening. Emerging battery chemistries will require adaptation of this methodology to new raw materials and impurity profiles.

Conclusion

The Agilent 5110 VDV ICP-OES with standard addition calibration provides a fast, accurate, and robust method for simultaneous quantification of 14 impurities in lithium carbonate. Its high sensitivity, excellent precision, and simplified workflow make it a valuable tool for routine quality assurance in lithium-ion battery production.

Reference

1. Agilent Technologies. Determination of Elemental Impurities in Graphite-based Anodes using the Agilent 5110 ICP-OES, Publication 5991-9508EN.
2. Agilent Technologies. Determination of Elements in Ternary Material Nickel-Cobalt-Manganese Hydride, Publication 5991-9506EN.
3. Agilent Technologies. Rapid Analysis of Elemental Impurities in Battery Electrolyte by ICP-OES, Publication 5994-1937EN.
4. IEC 62321:2008. Electrotechnical products – Determination of levels of six regulated substances.
5. GB/T 11064.16-2013. Methods for chemical analysis of lithium carbonate, Part 16: Inductively-coupled plasma atomic emission spectrometry.
6. Agilent Technologies. Fitted Background Correction (FBC)—fast, accurate and fully automated background correction, Publication 5991-4836EN.