Electrochemical reactions of lithium with transition metal nitride electrodes
Electrochemical reactions of lithium with transition metal nitride electrodes
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DOI：
10.1021/jp030530s
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发表时间：
2004-02-19
影响因子：
3.3
通讯作者：
Qin, QZ
中科院分区：
文献类型：
--
作者：
Fu, ZW;Wang, Y;Qin, QZ
采用反应脉冲激光沉积和直流放电相结合的方法，在氮气气氛中成功地制备了新型过渡金属氮化物Co 3 N和Fe 3 N薄膜。首次采用恒电流充放电、循环伏安和现场光谱电化学方法研究了Li在Co 3 N和Fe 3 N薄膜电极上的电化学反应。这些薄膜电极表现出324 mAh/g至420 mAh/g的可逆放电容量。采用X射线衍射（XRD）、X射线光电子能谱（XPS）和扫描电子显微镜（SEM）对沉积态、锂化态和脱锂态Co 3 N和Fe 3 N薄膜的结构、形貌和组成进行了表征。薄膜中金属Co（111）和Fe（110）的衍射峰表明，Li分别与Co 3 N和Fe 3 N反应生成的过渡金属Co和Fe具有良好的结晶性，XPS谱进一步证实了这一点。我们提出了一种新的反应机理，其中在第一次放电过程中形成的过渡金属Co和Fe的一部分被氮化，另一部分作为活跃的旁观者可能在随后的电化学反应中驱动Li 3 N的分解和形成中发挥主要作用。
Novel transition metal nitrides Of Co3N and Fe3N thin films have been successfully fabricated by combining reactive pulsed laser deposition and DC discharge in a nitrogen ambient. The electrochemical reactions of lithium with Co3N and Fe3N thin film electrodes were first investigated by the galvanostatic discharge and charge, cyclic voltammetry, and the in-situ spectroelectrochemical measurements. These thin film electrodes exhibited reversible discharge capacities ranging from 324 mAh/g to 420mAh/g. The structure, morphology, and composition of the as-deposited, lithiated, and delithiated Co3N and Fe3N thin films have been characterized by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and scanning electron microscopy (SEM). The observed diffraction peaks from metal Co(111) and Fe(110) in the lithiated thin films showed well crystallinity of transition metallic Co and Fe formed by Li reacted with Co3N and Fe3N, respectively, which could further be confirmed by their XPS spectra. We proposed a new reaction mechanism, in which part of the transition metallic Co and Fe formed during the first discharging is nitrided and another part as an active spectator may play a major role in driving the decomposition and formation of Li3N during the subsequent electrochemical reaction.