New Method Developed for Analysing the Electrode-Electrolyte Interphase

The electrode-electrolyte interphase can now be analysed under real conditions in a lithium-ion battery cell using infrared spectroscopy. The new method is made possible by an optimised measuring cell from a 3D printer.

31 January 2024 – Researchers from Helmholtz Institute Münster (HI MS; IEK-12) of Forschungszentrum Jülich and MEET Battery Research Center of the University of Münster have developed a new method for investigating the electrode-electrolyte interphase in lithium-ion batteries (LIB). It enables research into the electrode-electrolyte interphase (SEI) with and without electrolyte additives on silicon electrodes under real conditions.

Use of Additives Improves Performance

The new method shows that the use of the electrolyte additive 2-sulfobenzoic anhydride (2-SBA) in high-voltage pouch cells can increase the number of cycles by over 150 per cent and achieve an energy gain of over 120 per cent compared to standard electrolytes. The use of the additive enables the formation of an effective interphase on the anode surface. Undesirable processes, such as electrolyte decomposition and lithium deposition, are also suppressed.

"We developed an optimised measuring cell for our investigation and implemented it using 3D printing. We used operando attenuated total reflection Fourier transform infrared spectroscopy (ATR-FTIR) to characterise the SEI under real conditions in a LIB," explains Matthias Weiling from the Young Investigator Group Interfacial Spectroelectrochemistry at Helmholtz Institute Münster.

Using the method developed, it was also possible to detect various decomposition products of 2-SBA in the SEI on silicon at different cell voltages.

Holistic View Through Cooperation

Additional measurements and thus a holistic view of the processes at the SEI were made possible by cross-institute cooperation. Christian Lechtenfeld, Lars Frankenstein and Dr Sascha Nowak from MEET Battery Research Center made an important contribution to clarifying the reaction mechanisms and visualising the interphases. Among other things, IC-CD-MS, SEM and EDX measurements were used.

Study Available in Advanced Energy Materials

The researchers Matthias Weiling, Felix Pfeiffer, Dr Diddo Diddens, Jian-Fen Wang and Dr Masoud Baghernejad from Helmholtz Institute Münster (HI MS; IEK-12) at Forschungszentrum Jülich, together with Christian Lechtenfeld, Lars Frankenstein and Dr Sascha Nowak from MEET Battery Research Center of the University of Münster, have published the detailed results of their study as an open access article in the journal Advanced Energy Materials.