In situ analysis of commercial batteries based on plug-and-play multi-nuclear magnetic resonance spectroscopy and surface-scan imaging – BAMR

Advancing electrochemical energy storage devices relies on versatile analytical tools capable of revealing the molecular mechanisms behind the function and degradation of battery materials in situ. Nuclear magnetic resonance (NMR) spectroscopy and imaging have shown exceptional sensitivity to local environments and dynamics of electrochemically relevant elements. The jelly roll architecture remains the most energy-efficient design used in battery cells, but a significant challenge for NMR lies in the limited penetration of radio frequency (RF) fields through conductive casings and current collectors. In this project, we are developing an experimental approach, termed plug&play NMR, that allows for direct RF wave transmission through the battery terminals, enabling efficient excitation and detection of signals from active electrochemical materials. A specialized RF adapter transforms the battery into an NMR probe tunable across a broad range of Larmor frequencies. This adapter offers detailed insights into the chemical environments of electrochemically active elements and introduces new metrics for accurately assessing states of charge (SoC) and health (SoH). Preliminary tests revealed electrochemical transformations between intercalated and metallic forms of charge carriers such as lithium (Li) and sodium (Na), along with bulk magnetic susceptibility effects in electrodes of commercial pouch cells. The magnetism of battery cell components is a sensitive indicator of electrodes' chemistry, SoC, SoH, current distribution, and defects. Surface-scan MRI is an advanced approach to rapid and accurate mapping of magnetic field patterns at the external surface of the cell. A series of devices that combine plug&play NMR and surface-scan MRI capabilities will be designed and deployed to study the dendrite growth dynamics, magnetic phase transitions and solid-state ion transport in commercial cells using low- and high-field NMR spectrometers.