In situ NMR diffusion coefficients assessment of lithium ion conductor using electrochemical priors and Arrhenius constraint—A computational study

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• 作者：Liang Deng^a ; ^b ; ^{dengl@pku.edu.cn} ; ^{dengl@mail.iee.ac.cn} ; Wen-Hui Yang^b ; Xing Lyu^b ; Shu-Feng Wei^b ; Zheng Wang^b ; Hui-Xian Wang^b
• 关键词：Lithium ion conductor ; Diffusion coefficient ; Nuclear magnetic resonance ; Pulsed-field gradient ; Electrochemical priors
• 刊名：Chinese Chemical Letters
• 出版年：2017
• 出版时间：February 2017
• 年：2017
• 卷：28
• 期：2
• 页码：362-366
• 全文大小：902 K
• 卷排序：28

文摘

In situ NMR measurements of the diffusion coefficients, including an estimate of signal strength, of lithium ion conductor using diffusion-weighting pulse sequence are performed in this study. A cascade bilinear model is proposed to estimate the diffusion sensitivity factors of pulsed-field gradient using prior information of the electrochemical performance and Arrhenius constraint. The model postulates that the active lithium nuclei participating electrochemical reaction are relevant to the NMR signal intensity, when discharge rate or temperature condition is varying. The electrochemical data and the NMR signal strength show a highly fit with the proposed model according our simulation and experiments. Furthermore, the diffusion time is constrained by temperature based on Arrhenius equation of reaction rates dependence. An experimental calculation of Li4Ti5O12 (LTO)/carbon nanotubes (CNTs) with the electrolyte evaluating at 20 °C is presented, which the b factor is estimated by the discharge rate.