Transient interference-based spectroscopy for a molecular-bond-sensitive probe of lithium ion batteries

Abstract

The lack of effective methods to track in situ lithium-ion distribution and structural evolution remains a bottleneck in the battery industry, yet no techniques currently allow in situ dynamic detection of detrimental Li₂O under realistic conditions. Here, a molecular-bond-sensitive probe technique is developed by leveraging transient interference-based spectroscopy (TIBS). By creating structured plasma channels through nonlinear interference of multiple femtosecond laser filaments, we achieve extreme spatial confinement of laser pulses, enabling peak intensities above 10¹⁴ W cm⁻². This field directly ruptures molecular bonds through tunneling ionization and triggers Coulomb explosion, disintegrating materials into constituent elements and fragments while preserving molecular signature information. The resulting element-specific emissions allow intrinsic probing of the original chemical states and local environments. When coupled with machine learning algorithms, this technique enables precise identification of lithium concentration changes as low as 0.3%, making it particularly valuable for in situ monitoring of atomic-scale structural changes and distinguishing the Li₂O side product from active materials.