Determination of Dissolved Manganese in Lithium/Manganese Oxide Battery Electrolyte

Importance of the Topic

Understanding and quantifying dissolved manganese in lithium/manganese oxide battery electrolytes is critical because manganese dissolution reduces cycle life and compromises performance in Li/LiMn2O4 cells. Accurate measurement of trace Mn2+ supports quality control and informs cathode design to extend battery longevity.

Objectives and Study Overview

This work aims to develop a robust ion chromatography (IC) method using a reagent-free IC (RFIC) system with suppressed conductivity detection to accurately determine dissolved manganese in a simulated Li/LiMn2O4 electrolyte. The study evaluates chromatographic separation, method sensitivity, repeatability, and recovery under isocratic conditions with a methanesulfonic acid (MSA) eluent.

Methodology and Instrumentation

• Instrumentation: Thermo Scientific Dionex ICS-2100 RFIC system with AS-AP autosampler and Chromeleon CDS version 6.80 SR9.
• Columns: Dionex IonPac CG12A guard (4×50 mm) and CS12A analytical (4×250 mm).
• Eluent: 20 mM MSA generated by EGC III cartridge with CR-CTC II trap column; suppressed detection via Dionex CSRS 300 cation suppressor at 60 mA, 35 °C.
• Sample Preparation: Simulated electrolyte containing 1.12 M LiPF6 and 2 wt % vinylene carbonate in EC/EMC (1:1), diluted 1:50 with DI water; spiked with 5 mg/L Mn, followed by the same dilution.

Main Results and Discussion

The method achieved baseline separation of Mn2+ from common cations (Li+, Na+, NH4+, K+, Mg2+, Ca2+) within a 15-minute run. Calibration over 0.1–1.0 mg/L Mn yielded linear response (r2 = 0.9997) and good peak shape. A 20 µL injection of the 0.1 mg/L standard produced a clear Mn peak, demonstrating enhanced sensitivity compared with nonsuppressed direct conductivity methods. Analysis of spiked samples gave an average recovery of 103 % and RSD of 0.15 %, confirming accuracy and precision.

Benefits and Practical Applications

• High sensitivity and reproducibility for trace Mn in battery electrolytes.
• Minimal sample preparation and fully automated eluent generation reduce error and labor.
• Applicability to quality control in battery production and research on cathode degradation mechanisms.

Future Trends and Opportunities

Future developments may include coupling IC with mass spectrometry for speciation, real-time in-line monitoring of metal dissolution during cycling, expansion to other transition metal cathodes, and integration into high-throughput battery testing platforms. Advances in microfluidic IC systems could further reduce analysis times and reagent consumption.

Conclusion

This RFIC method provides a sensitive, accurate, and reproducible approach to quantify dissolved manganese in Li/LiMn2O4 electrolytes. The combination of isocratic MSA elution, suppressed conductivity detection, and automated eluent generation streamlines analysis and supports improved quality control and research in lithium-ion battery technology.

References

1. Thermo Scientific Application Note 258: Determination of Tetrafluoroborate, Perchlorate, and Hexafluorophosphate in a Simulated Electrolyte Sample from Lithium Ion Battery Production. Sunnyvale, CA, 2010.
2. Doh C., Lee J., Lee D., Jin B., Moon S. The Quantitative Analysis of the Dissolved Manganese in the Electrolyte of Li/LiMn2O4 Cell Using Ion Chromatography. Bull. Korean Chem. Soc. 2009, 30(10), 2429–2432.