Development of in situ high resolution NMR: Proof-of-principle for a new (spinning) cylindrical mini-pellet approach applied to a Lithium ion battery.

Solid-state nuclear magnetic resonance (ssNMR) spectroscopy is a powerful technique for characterizing the local structure and dynamics of battery and other materials. It has been widely used to investigate bulk electrode compounds, electrolytes, and interfaces. Beside common ex situ investigations, in situ and operando techniques have gained considerable importance for understanding the reaction mechanisms and cell degradation of electrochemical cells. Herein, we present the recent development of in situ magic angle spinning (MAS) NMR methodologies to study batteries with high spectral resolution, setting into context possible advances on this topic. A mini cylindrical cell type insert for 4 mm MAS rotors is introduced here, being demonstrated on a Li/VO 2 F electrochemical system, allowing the acquisition of high-resolution 7Li MAS NMR spectra, spinning the electrochemical cell up to 15 kHz. [Display omitted] • A new cylindrical mini pellet design introduced and demonstrated in situ MAS NMR study of a lithium ion battery. • This design permits stable spinning of battery pellets up to 15 kHz, improving practical spectral resolution by a factor of 50. • Two phases of lithiated V2OF were identified as Li x VO 2 F (x≤1) and Li x VO 2 F (x≤2). [ABSTRACT FROM AUTHOR]