Details

Autor(en) / Beteiligte

• Zhou, Lina
• Leskes, Michal
• Ilott, Andrew J.
• Trease, Nicole M.
• Grey, Clare P.

Titel

Paramagnetic electrodes and bulk magnetic susceptibility effects in the in situ NMR studies of batteries: Application to Li1.08Mn1.92O4 spinels

Ist Teil von

• Journal of magnetic resonance (1997), 2013-09, Vol.234, p.44-57

Ort / Verlag

United States: Elsevier Inc

Erscheinungsjahr

2013

Quelle

Alma/SFX Local Collection

Beschreibungen/Notizen

• [Display omitted] •Challenges of in situ NMR of Li-ion batteries containing paramagnetic electrodes are described.•The orientation dependence of BMS effects is evaluated using a dipolar coupling model.•The shape and packing density dependence of BMS effect of paramagnetic electrodes are discussed.•The BMS induced shift can be minimized by orienting the battery at a rotation angle of 54.7°. To date, in situ nuclear magnetic resonance (NMR) studies of working batteries have been performed in static mode, i.e., in the absence of magic angle spinning (MAS). Thus, it is extremely challenging to apply the method to paramagnetic systems such as the cathodes spinels Li1+xMn2−xO4 primarily due to three factors: (1) the resonance lines are broadened severely; (2) spectral analysis is made more complicated by bulk magnetic susceptibility (BMS) effects, which depend on the orientation and shape of the object under investigation; (3) the difficulty in untangling the BMS effects induced by the paramagnetic and metallic components on other (often diamagnetic) components in the system, which result in additional shifts and line broadening. Here we evaluate the orientation-dependence of the BMS effect of Li1.08Mn1.92O4, analyzing the experimental results by using a simple long-distance Li-electron dipolar coupling model. In addition, we discuss the shape and packing density dependence of the BMS effect and its influence on the observed frequencies of other components, such as the Li metal and the electrolyte in the battery. Finally, we show that by taking these effects into account we are able to minimize the BMS induced shift by orienting the cell at a rotation angle, αi=54.7° which facilitates the interpretation of the in situ NMR spectra of a working battery with the paramagnetic Li1.08Mn1.92O4 cathode.