Reversible lithium uptake by CoP3 at low potential: role of the anion
Reversible lithium uptake by CoP3 at low potential: role of the anion
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DOI：
10.1016/s1388-2481(02)00363-6
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发表时间：
2002-06
影响因子：
5.4
通讯作者：
V. Pralong;D. C. Souza;K. Leung;L. Nazar
中科院分区：
文献类型：
--
作者：
V. Pralong;D. C. Souza;K. Leung;L. Nazar
虽然V族中的各种过渡金属化合物（氮化物和锑化物）已被报道作为低电位Li插入宿主，但迄今为止磷化物仍未被开发。我们在这里展示了锂在金属磷化物CoP3中的吸收和提取，通过一种新的机制，在平均电位为0.9 V vs Li/Li+时提供了400 mAh/g的可逆容量。后者是利用x射线衍射、电子显微镜、动电位和恒流间歇测量以及x射线光电子能谱（XPS）相结合的方法发现的。Li的初始吸收形成高度分散的钴团簇，嵌入在Li3P基质中；从这种离子导电基质中带电提取Li可以得到纳米级的LiP，而Co位点的氧化态变化不大。这表明，与金属氧化物的情况相反，阴离子在还原和氧化中起主要作用。我们期望这是磷化物的普遍现象，并且在寻找新的负极材料方面具有根本的兴趣和未来的重要性。
Although various transition metal compounds in Group V (nitrides and antimonides) have been reported to act as low potential Li insertion hosts, the phosphides have remained unexplored to date. We show here that lithium uptake and extraction in the metal phosphide, CoP3, provides a reversible capacity of 400 mAh/g at an average potential of 0.9 V vs Li/Li+, via a novel mechanism. The latter was revealed using a combination of X-ray diffraction, electron microscopy, and potentiodynamic and galvanostatic intermittent measurements coupled with X-ray photoelectron spectroscopy (XPS). Initial uptake of Li forms highly dispersed cobalt clusters embedded in a matrix of Li3P; extraction of Li from this ion-conductive matrix on charge yields nano-particles of LiP, with little change evident in the oxidation state of the Co site. This shows that contrary to the case of metal oxides here the anion plays the major role in reduction and oxidation. We expect this is a general phenomenon for phosphides, and to be of fundamental interest and future importance in the search for new negative electrode materials.