Electrifying Insights: How GC-MS is Powering Lithium-Ion Battery Analysis

Lithium-ion batteries (LIBs) have transformed energy storage technology, driving innovations for products we use in everyday life such as smartphones and even electric vehicles. But what makes these batteries so efficient? A key component is the electrolyte solution, a complex mix that’s crucial for battery performance. GC-MS or gas chromatography-mass spectrometry is an essential tool in analyzing these electrolyte mixtures and the development of increased efficiency and longer-lasting batteries.

Thermo Fisher Scientific: Electrifying Insights: How GC-MS is Powering Lithium-Ion Battery Analysis.

Why Analyze Electrolytes?

Electrolyte solutions are the essence of lithium-ion batteries, impacting:

• Performance: The right mix ensures faster charging and longer battery life.
• Safety: Accurate composition prevents overheating and potential hazards.
• Lifespan: Understanding degradation helps design components that last longer.

Getting the electrolyte mix right is vital for efficient, safe, and durable batteries.

However, analyzing electrolytes is complex and comes with a number of challenges:

1. Complex Mixture: Electrolytes consist of various organic solvents, additives, and degradation products. This complexity requires sophisticated technology to separate and identify components.
2. Heat Sensitivity: Components like LiPF6 can degrade at high temperatures, creating new compounds that complicate analysis.
3. Trace Additives: Some additives are present in low concentrations but play a critical role in battery performance. Detecting these components demands highly sensitive methods.
4. Degradation Products: Battery cycling produces byproducts that can interfere with the main components. It’s like trying to find a book in a disorganized library.

This is where GC-MS becomes an essential analytical tool. This powerful technique provides a detailed look into the composition of LIB electrolytes. The analysis follows a number of steps:

• Sample Prep: LIB electrolyte samples are diluted in dichloromethane and centrifuged to remove interfering salts.
• GC Separation: Samples are run through a gas chromatograph which uses a programmed temperature ramp ensures all components are separated within a 23-minute window.
• MS detection: After separation, the mass spectrometer operating in full scan and selected ion monitoring (SIM) provides detailed qualitative and quantitative data.

Figure 1 shows the difference in selectivity between full scan and SIM mode. Vinylene carbonate is not detected in full scan at a 1 to 500 dilution due to the lack of selectivity and interference in full scan acquisition. However, by using SIM the ions of interest are isolated in the quadrupole increasing selectivity and allowing vinylene carbonate to be quantified at a low level.

Thermo Fisher Scientific: Figure 1. Full scan and SIM acquisition of vinylene carbonate in cycled LIB electrolyte at 1:500 dilution.

GC-MS brings several advantages to electrolyte analysis:

• Precise Separation: Achieves excellent separation of multiple components, ensuring accurate readings without co-elution issues.
• High Sensitivity: Detects even trace amounts of additives—down to 0.021 mg/L.
• Broad Range: Handles a wide concentration range, analyzing both major and minor components in one go.
• Degradation Insights: Reveals compositional shifts in cycled electrolytes, providing clues about the aging process of batteries.