摘要
Synchrotron-based x-ray absorption near-edge structure(XANES)spectroscopy is applied to investigate the variation of Ti valence in the discharge and charge processes of Li_(4)Ti_(5)O_(12).Through analysis of the XANES data,the average valence of Ti can be calculated,which allows quantitative determination of the ratios of Ti^(3+)/Ti^(4+) as a function of Li content in the electrodes.It is found that the ratios in the composites of Li_(4)Ti_(5)O_(12)/acetylene black(AB)-carbon are larger than those in Li_(4)Ti_(5)O_(12)/Ag/AB-carbon after the discharge to 1.1 V,indicating a larger amount of Li inserted into the former than that into the latter.This finding provides a good explanation for the fact that the Li_(4)Ti_(5)O_(12)/AB-carbon samples exhibit larger storage capacities than the Li_(4)Ti_(5)O_(12)/Ag/AB-carbon ones prepared in this work,concerning the larger Ti^(3+)/Ti^(4+) ratio and the larger amount of Li^(+) inserted in the electrode for satisfying the charge neutralization requirement.
作者
YU Peng-Fei
CUI Zhong-Hui
MENG Jian-Wei
GUO Xiang-Xin
于鹏飞;崔忠慧;孟建伟;郭向欣(State Key Laboratory of High Performance Ceramics and Superfine Microstructure,Shanghai Institute of Ceramics,Chinese Academy of Sciences,Shanghai 200050;State Key Laboratory of ASIC and System,Department of Microelectronics,Fudan University,Shanghai 200433)
基金
Supported by the National Natural Science Foundation of China under Grant Nos 10979069,U1232111,the One-Hundred Talents Project of Chinese Academy of Sciences.
