Carbothermal synthesis, spectral and magnetic characterization and Li-cyclability of the Mo-cluster compounds, LiYMo3O8 and Mn2Mo3O8
Carbothermal synthesis, spectral and magnetic characterization and Li-cyclability of the Mo-cluster compounds, LiYMo3O8 and Mn2Mo3O8
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DOI：
10.1016/j.electacta.2008.12.049
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发表时间：
2009-04-30
影响因子：
6.6
通讯作者：
Chowdari, B. V. R.
中科院分区：
文献类型：
--
作者：
Das, B.;Reddy, M. V.;Chowdari, B. V. R.
采用碳热还原法制备了钼簇合物LiYMo3O8和Mn2Mo3O8，并对其进行了表征。首次报道了常温红外光谱和不同温度(78-450K)下的拉曼光谱，并对结果进行了解释。对Mn2Mo3O8在10-350K温度范围内的磁学研究证实，它是亚铁磁性的，T-C=39K，给出了不同磁场和温度下的磁滞和磁化强度数据。在该电压范围内，通过恒流循环研究了锂离子电池的循环性能。0.005-3.0V与锂在30 mA/g(0.08C)下。LiYMo3O8的首次放电总容量为305+/-5mAh/g，而首次充电容量仅为180mAh/g。然而，随着循环次数的增加，这两个值都有系统地增加，在第120次循环结束时，产生的可逆容量为385.5mAh/g。在50℃时，第60次循环的可逆容量为418+/-5mAh/g。库仑效率在94%~98%之间。Mn2Mo3O8的锂循环行为与LiYMo3O8完全不同。首次放电和充电总容量分别为710+/-5和565+/-5mAh/g，但循环过程中容量衰减严重。50次循环结束时的可逆容量仅为205+/-5mAh/g。基于恒半乳糖循环、循环伏安、非原位X射线衍射、非原位透射电子显微镜和阻抗谱数据，提出并讨论了可能的反应机理。(C)爱思唯尔有限公司出版的2009年。
The molybdenum cluster compounds, LiYMo3O8 and Mn2Mo3O8 are prepared by the carbothermal reduction method and characterized by various techniques. The FT-IR at ambient temperature (RT), and Raman spectra at various temperatures (78-450 K) are reported for the first time and results are interpreted. Magnetic studies on Mn2Mo3O8 in the temperature range, 10-350 K confirm that it is ferrimagnetic, with T-C = 39 K. Magnetic hysteresis and magnetization data at various fields and temperatures are presented. The Li-cyclability is investigated by galvanostatic cycling in the voltage range. 0.005-3.0V vs. Li at 30 mA/g (0.08 C). LiYMo3O8 shows a total first-discharge capacity of 305 +/- 5 mAh/g whereas the first-charge capacity is only 180 mAh/g at RT. However, both values increased systematically with an increase in the cycle number and yielded a reversible capacity of 385 5 mAh/g at the end of 120th cycle. At 50 degrees C, the reversible capacity is 418 +/- 5 mAh/g at the 60th cycle. The coulombic efficiency ranges from 94% to 98%. The Li-cyclability behavior of Mn2Mo3O8 is entirely different from that of LiYMo3O8. The total first-discharge and charge capacities are 710 +/- 5 and 565 +/- 5 mAh/g, but drastic capacity-fading occurs during cycling. The reversible capacity at the end of 50th cycle is only 205 +/- 5 mAh/g. Plausible reaction mechanisms are proposed and discussed based on the galavanostatic cycling, cyclic voltammetry, ex situ XRD, ex situ TEM and impedance spectral data. (C) 2009 Published by Elsevier Ltd.