Better Cycling Performances of Bulk Sb in Na-Ion Batteries Compared to Li-Ion Systems: An Unexpected Electrochemical Mechanism
Better Cycling Performances of Bulk Sb in Na-Ion Batteries Compared to Li-Ion Systems: An Unexpected Electrochemical Mechanism
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DOI：
10.1021/ja310347x
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发表时间：
2012-12-26
影响因子：
15
通讯作者：
Monconduit, Laure
中科院分区：
文献类型：
--
作者：
Darwiche, Ali;Marino, Cyril;Monconduit, Laure
纯微量锑可以成功地用作钠离子电池的负极材料，在高速率下保持接近600 rnag（-1）的容量，库仑效率为99 / 160循环，与任何其他对Li和Na进行测试的化合物相比，这是一个非常高的容量。与Na的反应机制不是简单地通过观察到的Li的合金化机制，其中中间物质是相图中预期的那些。在Na的情况下，中间相大多是无定形的，不能精确地识别。令人惊讶的是，我们证明了在Sb/Na电池放电结束时，在Na3Sb的六边形多晶和立方多晶的形成之间发生了竞争，最后在文献中被描述为在大气压下不稳定，只能在高压（1-9 GPa）下合成。此外，在电解质中加入氟乙烯碳酸酯，并结合以羧甲基纤维素、炭黑和蒸汽磨碳纤维为基础的适当电极配方，似乎是决定该材料优异性能的决定性因素。
Pure micrometric antimony can be successfully used as negative electrode material in Na-ion batteries, sustaining a capacity close to 600 rnAh g(-1) at a high rate with a Coulombic efficiency of 99 over 160 cycles, an extremely high capacity compared to any other compound tested against both Li and Na. The reaction mechanism with Na does not simply go through the alloying mechanism observed for Li where the intermediate species are those expected from the phase diagram. In the case of Na, the intermediate phases are mostly amorphous and could not be precisely identified. Surprisingly, we evidenced that a competition takes place at the end of the discharge of the Sb/Na cell between the formation of the hexagonal and the cubic polymorphs of Na3Sb, the last being described in the literature as unstable at atmospheric pressure and only synthesized under high pressure (1-9 GPa). In addition, fluoroethylene carbonate added to the electrolyte combined with an appropriate electrode formulation based on carboxymethyl cellulose, carbon black, and vapor ground carbon fibers seems to be determinant in the excellent performances of this material.