Molecular Level Structure and Dynamics of Electrolytes Using¹⁷O Nuclear Magnetic Resonance Spectroscopy

In situ and ex situ NMR for battery research

“…Due to the empirical nature of these models, a more theoretical approach could provide a deeper understanding of diffusion in electrolyte systems. To support measurements of structure and diffusion, computational MD predictions of the diffusion constants can be well-matched with experimental values [232]. In this way, computational efforts that are not DFT-based have also played an important role in characterizing electrolyte systems.…”

“…Other sensitivity enhancement techniques, notably, the technique of dynamic nuclear polarization (DNP) that can potentially increase an NMR signal by up to 2-4 orders of magnitude via transferring paramagnetic electron polarization from a polarization agent by taking advantage of the much larger electron Zeeman interaction [238][239][240], may further help to advance the application of NMR in energy storage research. One final area that lacks extensive literature is the detailed time scale information on various processes that NMR can probe [232]. Such information will provide unprecedented insight into the interaction mechanisms and molecular motion at play within these systems.…”

Lithium Speciation in the LiPF6/PC Electrolyte Studied by Two-Dimensional Heteronuclear Overhauser Enhancement and Pulse-Field Gradient Diffusometry NMR

“…Li-ion complexation in nonaqueous carbonate solvents has been examined by several techniques such as Raman, − vibrational, infrared, , and molecular rotation spectroscopies . Nuclear magnetic resonance (NMR) spectroscopy ,− has also been used to glean valuable atomic level insights from the observed changes in the chemical shifts of 13 C and 17 O of the solvent molecule upon complexation with the lithium cation. Molecular dynamics simulations and density functional theory as well as quantum chemical calculations have been employed to understand the nature of the interaction between the lithium cation and the carbonate solvent.…”

“…NMR spectroscopy is an effective molecular characterization tool which aids to probe the solvent, cation and anion environments in the electrolyte at the atomic level. NMR inspection of the solvent molecules is facilitated through the observation of 1 H, 13 C, and 17 O nuclei, and in the solvent-dominated regime, the details of cation solvation can be directly inferred from these studies. ,,, Similarly, 7 Li NMR provides a direct access to probe the lithium cation environments with a very high detection sensitivity because of its high natural abundance (92.6%). Despite being quadrupolar ( I = 3/2), a high signal resolution is also guaranteed in the observed NMR spectra because of its small quadrupole moment ( Q = −40.1 mbarn) and the complete averaging of the electric field gradient tensor in the isotropic solution phase.…”