Destabilization of LiH by Li insertion into Ge
Destabilization of LiH by Li insertion into Ge
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Li插入Ge导致LiH不稳定
DOI：
10.1021/jp400133t
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发表时间：
2013
影响因子：
3.7
通讯作者：
Yoshitsugu Kojima
中科院分区：
文献类型：
--
作者：
Ankur Jain;Erika Kawasako;Hiroki Miyaoka;Tao Ma;Shigehito Isobe;Takayuki Ichikawa;Yoshitsugu Kojima
氢化锂具有高的氢容量（12.7质量%），但由于非常稳定（对于0.1MPa的解吸压力需要900 ℃），因此不能被认为是实用的储氢介质。最近，已经发现C和Si适合于降低LiH的稳定性。这促使我们研究与其他元素形成的Li的其他合金的性质。采用机械球磨法制备了Li3.75Ge（Li 15 Ge 4）合金，在400 °C真空加热过程中，合金转变为Li4.2Ge（Li21.1875Ge5）和Li3.5Ge（Li 7 Ge 2）相。在PCI实验期间，在400 °C和3 MPa氢压下对由此形成的合金进行加氢，将该混合相转化为Li2GeH0.5（Li 4Ge 2 H）和LiH相。从TG-DTA-MS实验中观察到，通过制备具有Ge的上述合金，观察到脱附温度显著降低（约300-450 °C）。还使用范特霍夫图计算了反应的焓。最后，利用能斯特方程和范特霍夫方程建立了储氢参数与电化学参数之间的直接关系。通过两种方法获得的锂化/脱锂所需的电位值之间存在良好的一致性。
Lithium hydride has high hydrogen capacity (12.7 mass %), but could not be considered as practical hydrogen storage media because of being very stable (required 900 °C for 0.1 MPa desorption pressure). Recently, C and Si have been found suitable to reduce the stability of LiH. This motivates us to investigate the properties of other alloys of Li, formed with the other elements. In the present work, Li3.75Ge (Li15Ge4) alloy was synthesized by mechanical milling, which transformed into Li4.2Ge (Li21.1875Ge5) and Li3.5Ge (Li7Ge2) phases during the vacuum heating at 400 °C. Hydrogenation of thus formed alloys at 400 °C under 3 MPa hydrogen pressure during PCI experiment transforms this mixed phase into Li2GeH0.5(Li4Ge2H) and LiH phase. A remarkable decrease in the desorption temperature (∼300–450 °C) is observed by preparing the above alloy with Ge as observed from TG-DTA-MS experiment. The enthalpy of the reaction has also been calculated using the van’t Hoff plot. The present work concluded with the establishment of a direct relationship between hydrogen storage parameters and electrochemical parameters using the Nernst equation and van’t Hoff equation. A good agreement is found between the values of required potential for lithiation/delithiation as obtained by two methods.