Baek, Seung-Ho ; Reinold, Lukas Mirko ; Graczyk-Zajac, Magdalena ; Riedel, Ralf ; Hammerath, Franziska ; Büchner, Bernd ; Grafe, Hans-Joachim (2014)
Lithium dynamics in carbon-rich polymer-derived SiCN ceramics probed by nuclear magnetic resonance.
In: Journal of Power Sources, 253
doi: 10.1016/j.jpowsour.2013.12.065
Article, Bibliographie

Abstract

We report 7Li, 29Si, and 13C NMR studies of two different carbon-rich SiCN ceramics SiCN-1 and SiCN-3 derived from the preceramic polymers polyphenylvinylsilylcarbodiimide and polyphenylvinylsilazane, respectively. From the spectral analysis of the three nuclei, we find that only the 13C spectrum is strongly influenced by Li insertion/extraction, suggesting that carbon phases are the major electrochemically active sites for Li storage. Temperature (T) and Larmor frequency (ωL) dependences of the 7Li linewidth and spin-lattice relaxation rates View the MathML source are described by an activated law with the activation energy EA of 0.31 eV and the correlation time τ0 in the high temperature limit of 1.3 ps. The 3/2 power law dependence of View the MathML source on ωL which deviates from the standard Bloembergen, Purcell, and Pound (BPP) model implies that the Li motion on the μs timescale is governed by continuum diffusion mechanism rather than jump diffusion. On the other hand, the rotating frame relaxation rate View the MathML source results suggest that the slow motion of Li on the ms timescale may be affected by complex diffusion and/or non-diffusion processes.

Send an inquiry

Show editorial Details