Scientists at Berkley Lab have used a novel technique to view the inner workings of the solid-electrolyte interphase (SEI) layer in an attempt to better understand how to improve lithium-ion battery electrolytes.
Researchers coupled on-electrode chromatography with matrix-assisted laser desorption/ionisation (MALDI) at the institute’s Molecular Foundry to separate and illustrate the structures of large organic molecules generated during battery operation.
Designing a better electrolyte system would enable the move to next-generation batteries, said battery scientist Gao Liu, the study’s corresponding author alongside Yi Liu of the Molecular Foundry.
He said: “The current electrolyte system works very well at ambient temperatures and with existing battery chemistries.
“However, the current electrolytes do not work well with the high energy density batteries, high-voltage batteries, or batteries working in extreme cold and with extreme fast charging.”
The study was published in the journal Joule.
The team said the technique, developed by its Energy Technologies Area department, revealed a new dimension of chemical composition inside lithium-ion batteries that enabled a new direction for rational engineering of the battery’s electrolyte system.
On-electrode chromatography uses the electrode as the stationary phase for fractionating the molecules on the electrode surfaces, consequently realising separation of different molecular species prior to MALDI analysis.
This coupled approach, used successfully for the first time in battery research, provides a simple and universal solution for the identification of the organic components in SEIs, including their structures and weight distributions, say the scientists.
Image: A scientist works on the MALDI (matrix-assisted laser desorption/ionization) mass spectrometer at Berkeley Lab’s Molecular Foundry. (Credit: Thor Swift/Berkeley Lab)