Cylindrical cells for sensitivity enhancement in operando NMR of batteries – CYCLONE

Operando NMR is a powerful technique for atomic-level characterization of the operating mechanisms and limitations of rechargeable batteries. However, such experiments are strongly limited in sensitivity, preventing studies of low-sensitivity nuclei, minority species, and fast-charging processes.

This project aims at increasing the sensitivity of operando NMR experiments on batteries through the implementation of a cylindrical cell configuration. This configuration will drastically increase the amount of active material in the cell and therefore enhance the sensitivity of operando NMR measurements, enabling a number of experiments that were previously not feasible. Within this project, cylindrical cells will be implemented and optimized, and two such studies will be performed for the first time.

First, the growth of the solid-electrolyte interphase (SEI) will be investigated. The understanding of SEI formation is essential for achieving long battery lifetimes, but operando studies are extremely challenging due to the very low SEI concentration. Using optimized cylindrical cells, we will perform operando NMR studies of SEI formation for the first time and provide important information for improving the SEI and batteries.

Second, we will monitor the formation of metastable phases in LiFePO4 (LFP) cathodes during fast charging. These metastable phases are still poorly characterized and have never been observed in operando NMR. The use of cylindrical cells will provide us with the necessary sensitivity and time resolution to characterize these transient phases, which will contribute to the application of LFP in fast-charging batteries.