Properties of a novel hard-carbon optimized to large size Li ion secondary battery studied by 7Li NMR
Properties of a novel hard-carbon optimized to large size Li ion secondary battery studied by 7Li NMR
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DOI：
10.1016/j.jpowsour.2006.09.001
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发表时间：
2006-11
影响因子：
9.2
通讯作者：
Kazuma Gotoh;Mariko Maeda;A. Nagai;A. Goto;M. Tansho;K. Hashi;T. Shimizu;H. Ishida
中科院分区：
文献类型：
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作者：
Kazuma Gotoh;Mariko Maeda;A. Nagai;A. Goto;M. Tansho;K. Hashi;T. Shimizu;H. Ishida
采用7li核磁共振方法，研究了一种新型硬碳材料在大尺寸锂离子二次电池负极中的锂离子状态，并与现有硬碳样品进行了比较。在静态核磁共振光谱中，新材料在室温下在85ppm处出现峰值，在7ppm处出现肩信号，在180K时，前者移至210ppm。后者在室温下归因于样品中含有掺杂Li的小颗粒。与其他硬碳样品相比，新碳样品的核磁共振簇锂信号强度较弱，这与电化学评价充放电曲线的恒压（CV）容量较小的趋势相对应。较小的CV容量和初始不可逆容量是新型硬碳的特征，这被认为是Li向碳孔扩散的阻碍。
The state of lithium in a novel hard-carbon optimized to the anode of large size Li ion secondary battery, which has been recently commercialized, was investigated and compared with other existing hard-carbon samples by7Li NMR method. The new carbon material showed a peak at 85ppm with a shoulder signal at 7ppm at room temperature in static NMR spectrum, and the former shifted to 210ppm at 180K. The latter at room temperature was attributed to Li doped in small particles contained in the sample. The new carbon sample showed weaker intensity of cluster-lithium signal than the other hard-carbon samples in NMR, which corresponded to a tendency of less “constant voltage” (CV) capacity in charge–discharge curves of electrochemical evaluation. Smaller CV capacity and initial irreversible capacity, which are the features of the novel hard-carbon, are considered to correspond to a blockade of the diffusion of Li into pore of carbon.