Operando spectra of a battery often consists of strongly overlapping resonances due to the compositional complexity and a mix of broad resonances. In the case of NMR spectroscopy, one could appeal to magic angle spinning (MAS) to remove some of these line broadenings and improve resolution. Unfortunately, eddy currents arising in metallic current collectors as well as in metallic electrode materials pose numerous experimental challenges.

Reported herein is an NMR method we developed that (1) improves the resolution of overlapping resonance which allows the identification of closely related features, but more importantly, the method (2) enhances the signals due to the formation and removal of species during the cycling of a battery. These spectra not only provide better resolution but also offer a more direct comparison of the species that are formed to the electrochemical current measured at each potential/time and reveal which spectra components are correlated to the chemical transformation at a specific potential.