CHAPTER 3: Dealing with Quadrupolar Nuclei in Paramagnetic Systems

Quadrupolar nuclei with spin quantum number I > 1/2, e.g. 7Li, 23Na and 17O, are frequently encountered in lithium-ion batteries and sodium-ion batteries. This chapter describes: (i) the basic theory, (ii) the powder sample line-shapes with first- and second-order quadrupolar broadening observed under static or MAS conditions, (iii) some important experimental techniques such as MQMAS, and finally (iv) the developments of correlation NMR experiments. In recent years, solid-state nuclear magnetic resonance spectroscopy (SS-NMR) has become a vital analytical method that provides atomic-level structural information of materials used for Li-ion and Na-ion batteries.1 In these materials, 7Li, 23Na and 17O isotopes are frequently encountered, which are typical quadrupolar nuclei with spin quantum number I > 1/2. In fact, quadrupolar nuclei account for ca. 75% of all NMR-active nuclei in the periodic table, and they are very important for SS-NMR structural analyses. This chapter describes: (i) the basic theory, (ii) the powder sample line-shapes with first- and second-order quadrupolar broadening observed under static or MAS conditions, (iii) some important experimental techniques such as MQMAS, and finally (iv) the developments of correlation NMR experiments.