This work is a step towards understanding the electrochemistry of energy storage devices like Lithium-Ion Capacitors (LICs) and Li-air batteries, by employing Nuclear Magnetic Resonance (NMR) Spectroscopy as a non-destructive tool, revealing the chemical environment of the molecules, giving valuable information about the molecular structure and electrochemical interactions.

An effort has been made to briefly illustrate the operating principles of NMR technique and instrumentation, while highlighting its diverse applications, with an emphasis on energy storage device characterization.

In situ 7Li NMR experiments on the LIC and Li-O2 battery were conducted by simultaneously cycling the samples specially developed for this purpose. NMR spectra recorded over multiple charge/discharge cycles of LIC reveal the 7Li NMR signals arising from different parts of the capacitor. We have been able to attribute the signals arising from the Li-metal, electrolyte and the intercalated Li and double layer using Gaussian-lorentian peak fit. The 7Li NMR spectra recorded for Li-O2 battery, which is a first for this chemistry, reveal a gradual increase in the area of a broad peak observed with the increase in cycling, pointing towards the gradual accumulation of discharge products in the porous carbon cathode and provides an insight into its reversibility/non-reversibility nature. The broad NMR spectra of the washed cathode confirms a combination (peroxide, oxide) of the discharge products of Li.