Probing the Mechanism of Sodium Ion Insertion into Copper Antimony Cu2Sb Anodes

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• 作者：Lo茂c Baggetto ; Kyler J. Carroll ; Hien-Yoong Hah ; Charles E. Johnson ; David R. Mullins ; Raymond R. Unocic ; Jacqueline A. Johnson ; Ying Shirley Meng ; Gabriel M. Veith
• 刊名：Journal of Physical Chemistry C
• 出版年：2014
• 出版时间：April 17, 2014
• 年：2014
• 卷：118
• 期：15
• 页码：7856-7864
• 全文大小：502K
• 年卷期：v.118,no.15(April 17, 2014)
• ISSN：1932-7455

文摘

We report experimental studies to understand the reaction mechanism of the intermetallic anode Cu₂Sb with Na and demonstrate that it is capable of retaining about 250 mAh g^鈥? over 200 cycles when using fluoroethylene carbonate additive. X-ray diffraction data indicate during the first discharge the reaction leads to the formation of crystalline Na₃Sb via an intermediate amorphous phase. Upon desodiation the Na₃Sb reverts to an amorphous phase, which then recrystallizes into Cu₂Sb at full charge, indicating a high degree of structural reversibility. The structure after charging to 1 V is different from that of Cu₂Sb, as indicated by X-ray absorption spectroscopy and ¹²¹Sb M枚ssbauer spectroscopy, and is due to the formation of an amorphous Na鈥揅u鈥揝b phase. At full discharge, an isomer shift of 鈭?.10 mm s^鈥? is measured, which is close to that of a Na₃Sb reference powder (鈭?.95 mm s^鈥?) and in agreement with the formation of Na₃Sb domains. During charge, the isomer shift at 1 V (鈭?.29 mm s^鈥?) is closer to that of the pristine material (鈭?.67 mm s^鈥?), but the lower value is consistent with the lack of full desodiation, as expected from the potential profile and the XAS data.