An effective stochastic excitation strategy for finding elusive NMR signals from solids

Investigating the Structure of an Active Material–Carbon Interface in the Monoclinic Li3V2(PO4)3/C Composite Cathode

“…To further understand the nature of the 0 and 70 ppm signals, 7 Li NMR at a higher spinning speed of 60 kHz and 2D exchange 7 Li NMR were employed, and the data are shown in Figure b,c. It is well-known that fast magic-angle spinning can generate frictional heat, which will increase the sample temperature. , In the 7 Li MAS NMR spectra acquired at 60 kHz, the three resonances of LVP coalesced and became broader due to faster Li + exchange at higher temperatures. Taking the spectra of pure LVP as a reference, we notice that the broadening and coalescence of the LVP/G composite is similar to that of pure LVP, whereas that of the LVP/CA, LVP/Glu, and LVP/GO composites is much more severe, suggesting higher mobility of Li + in these samples.…”

Strategies for Solid-State NMR Studies of Materials: From Diamagnetic to Paramagnetic Porous Solids

“…Wilke and coworkers have suggested another technique based on the so-called stochastic pulse sequences combined with high magic-angle spinning rates to observe the broad and largely shifted resonances. They have used low power, approximately 1° pulses acting stochastically 0° and 180° out of phase relative to one another, and measured the shift of 31 P nuclei in paramagnetic solid LiNiPO 4 equal to 1726 ppm.…”

Structural Characteristics of Lithium Nickel Phosphate Studied Using Analytical Electron Microscopy and Raman Spectroscopy

“…Recently, there has been a great deal of interest in lithium nickel phosphates. Different aspects, such as synthesis, structural and vibrational properties, electrochemistry, and magnetism, of these materials have been studied by various research groups using both experimental and theoretical invetigations. − The advancement in lithium battery technology is envisaged on the basis of lithium metal phosphate materials as cathode materials. ,,− The first principle calculations, using various approaches, have confirmed the high electrochemical potentials of LiNiPO 4 , which makes them attractive for application in lithium battery technology. − The extensive contributions of Ceder's research group using first principles computations, which are based on local density approximation (LDA) and generalized gradient approximation (GGA), have predicted the Li intercalation potential of LiNiPO 4 to be above 5 V. , Wolfenstine and Allen have recently performed experiments and verified the higher potentials predicted by theoretical predications . On the other hand, alternate methods such as formation of a nano-network of metal phosphides, metal phosphocarbides, and/or amorphous carbon at grain boundaries have been proposed to increase the electrical conductivity of these materials .…”