Assessing the purity grade of lithium carbonate and lithium hydroxide using ICP-OES

Importance of the Topic

Lithium carbonate (Li2CO3) and lithium hydroxide (LiOH) are key precursors in lithium-ion battery production. Ensuring their high purity is critical for battery performance, safety and lifespan. Rapid, multi-element impurity analysis supports manufacturers in quality control, increases material value and reduces downstream processing risks.

Objectives and Study Overview

This study demonstrates the capability of the Thermo Scientific iCAP PRO XP ICP-OES Duo to quantify 45 trace elements in Li2CO3 and LiOH in a single analytical run. It aims to validate sensitivity, accuracy, robustness and throughput for routine industrial quality control of battery-grade lithium salts.

Methodology Overview

• Sample preparation: 250 mg of lithium salt was digested in trace-metal nitric acid, diluted to 50 mL with ultra-pure water.
• Calibration: matrix-matched standards containing 1 g·L⁻¹ lithium and 50–2000 µg·L⁻¹ analyte concentrations; yttrium (5 mg·L⁻¹) used as internal standard.
• Validation: spike recoveries at 50 µg·L⁻¹ and 1 mg·L⁻¹ levels; continuous analysis over 12 hours for robustness testing.

Instrumentation Used

Thermo Scientific iCAP PRO XP ICP-OES Duo operated in intelligent full-range (iFR) axial mode. Key components:

• Ceramic D-torch for enhanced matrix tolerance
• Glass cyclonic spray chamber and standard glass nebulizer
• Qtegra ISDS software for data acquisition and processing

Typical operating parameters included 1,350 W RF power, 0.55 L·min⁻¹ nebulizer flow, 14.5 L·min⁻¹ coolant flow, 15 s exposure and three replicates per sample.

Main Results and Discussion

• Linearity: R² > 0.9996 for all elements across three orders of magnitude.
• Detection limits: MDLs below 1 mg·L⁻¹ for 43 of 45 elements; 19 elements < 0.01 mg·L⁻¹.
• Accuracy: spike recoveries within ±20%; QC recoveries within 80–120%.
• Robustness: stable internal standard recovery (90–100%) and QC performance over a 12 h sequence.
• Sample profiling: high-purity Li2CO3 and LiOH exhibited distinct alkaline and alkaline-earth impurity patterns consistent with purity specifications.

Benefits and Practical Applications

• Rapid throughput: 144 s per sample for full multi-element quantification.
• Comprehensive screening: simultaneous analysis of 45 elements reduces run times and labor.
• Robust performance: ceramic torch and matrix matching minimize maintenance and interferences.
• Quality assurance: reliable data for raw material certification and process control in battery manufacturing.

Future Trends and Possibilities

• Extension to ICP-MS for sub-µg·L⁻¹ detection of ultra-trace impurities.
• Automated sample preparation and inline QC for high-throughput manufacturing.
• Integration with digital data management and AI-driven analytics for predictive process control.
• Adaptation to emerging battery chemistries requiring new impurity profiles.

Conclusion

The iCAP PRO XP ICP-OES Duo offers a fast, sensitive and robust solution for routine multi-element impurity analysis of Li2CO3 and LiOH. Its high throughput, excellent detection limits and stability make it an effective tool for ensuring the quality of battery-grade lithium salts in industrial laboratories.