Lithium dynamics in carbon-rich polymer-derived SiCN ceramics probed by nuclear magnetic resonance

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• 作者：Seung-Ho Baek ; Lukas Mirko Reinold ; Magdalena Graczyk-Zajac ; Ralf Riedel ; Franziska Hammerath ; Bernd B眉chner ; Hans-Joachim Grafe
• 关键词：Nuclear magnetic resonance (NMR) ; 7Li dynamics ; Anode ; Lithium-ion battery ; Silicon carbonitride ; Polymer-derived ceramic
• 刊名：Journal of Power Sources
• 出版年：1 May, 2014
• 年：2014
• 卷：253
• 期：Complete
• 页码：342-348
• 全文大小：684 K

文摘

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 () dependences of the ⁷Li linewidth and spin-lattice relaxation rates are described by an activated law with the activation energy of 0.31 eV and the correlation time in the high temperature limit of 1.3 ps. The power law dependence of on which deviates from the standard Bloembergen, Purcell, and Pound (BPP) model implies that the Li motion on the 渭s timescale is governed by continuum diffusion mechanism rather than jump diffusion. On the other hand, the rotating frame relaxation rate results suggest that the slow motion of Li on the ms timescale may be affected by complex diffusion and/or non-diffusion processes.