Automated salt removal and dilution for online analysis of unprocessed lithium battery electrolytes using gas chromatography-mass spectrometry

Importance of the Topic

Lithium ion battery performance and safety depend on precise electrolyte composition. Comprehensive analysis of unprocessed electrolytes is essential for quality control, aging studies, and reliable battery operation. Automated workflows reduce manual variability and increase throughput compared to traditional sample preparation.

Objectives and Study Overview

This technical note presents a fully automated method for the analysis of unprocessed lithium battery electrolytes. The approach employs an autosampler to remove lithium salt by precipitation and centrifugation, followed by controlled dilution up to a total factor of 10 000. It supports the detection of major solvents, common additives, and low-level degradation products using gas chromatography-mass spectrometry.

Methodology and Instrumentation

The workflow consists of two sequential steps. Step 1 adds a small aliquot of electrolyte to dichloromethane in a vial, vortex mixes, and centrifuges to precipitate LiPF6. The supernatant is then transferred for analysis or further dilution. Step 2 optionally dilutes the supernatant with additional dichloromethane to adjust concentrations of abundant components. Automated tool changes enable use of three syringe volumes. Samples are injected into a gas chromatograph coupled to a triple quadrupole mass spectrometer under full scan for major solvents and selected reaction monitoring for trace analytes.

Instrumentation

• TriPlus RSH SMART autosampler
• TRACE 1610 gas chromatograph
• TSQ 9610 triple quadrupole mass spectrometer

Main Results and Discussion

Repeatability was evaluated with eight identical aliquots of electrolyte. Relative standard deviations for ethyl methyl carbonate and ethylene carbonate peak areas were below 6 percent. Automated syringe rinsing prevented detectable carryover in blank injections. Spike recovery tests for ten representative additives and degradation products yielded reproducible recoveries between 61 and 83 percent. A complete sample preparation cycle requires approximately 18 minutes, fully overlapping with the preceding GC run to maximize throughput.

Benefits and Practical Application

The automated workflow ensures consistent and unbiased sample treatment, reduces hands-on time, and protects the GC column from salt damage. It enables simultaneous analysis of high-concentration solvents and trace components in a single sequence, making it suitable for routine quality assurance in battery manufacturing and research laboratories.

Future Trends and Potential Uses

Future enhancements may include real-time adaptive dilution protocols, integration with high resolution mass spectrometry, and coupling with data analytics for predictive degradation studies. Expansion to alternative electrolyte systems and remote operation could further support advanced battery diagnostics.

Conclusion

The proposed automated salt removal and dilution workflow offers a reliable, high-throughput solution for GC-MS analysis of unprocessed lithium battery electrolytes. It ensures reproducible quantitation across a wide concentration range and streamlines quality control and research workflows.

Reference

1. Thermo Fisher Scientific Application Note 001124 Comprehensive analysis of electrolyte solutions for lithium ion batteries using gas chromatography mass spectrometry