Electrochemical properties and hydrogen storage mechanism of perovskite-type oxide LaFeO3 as a negative electrode for Ni/MH batteries

Perovskite-type oxide LaFeO3 powder was prepared using a stearic acid combustion method. Its phase structure, electrochemical properties and hydrogen storage mechanism as negative electrodes for nickel/metal hydride (Ni/MH) batteries have been investigated systematically. The results of X-ray diffraction (XRD) analysis show that both the calcined powder and the charged/discharged samples after 10 cycles have orthorhombic structures. The discharge capacity, whose maximum value appeared at the first cycle, is 530.3 mA h g(-1) at 333 K and increases with an increase in temperature. The discharge capacity decreases distinctly during the first three cycles and then stays steady at about 80 mA h g(-1), 160 mA h g(-1) and 350 mA h g(-1) at 298 K, 313 K and 333 K, respectively. The hydrogen storage mechanism is studied by XRD, X-ray photoelectron spectroscopy (XPS) and mass spectrometry (MS), coupled with pressure-composition-temperature (PCT) methods. Hydrogen atoms may be intercalating into the oxide lattice and forming a homogeneous solid solution during the charging process. Crown Copyright (C) 2009 Published by Elsevier Ltd. All rights reserved.

采用硬脂酸燃烧法制备了钙钛矿型氧化物LaFeO₃粉末。系统地研究了其作为镍/金属氢化物（Ni/MH）电池负极的相结构、电化学性能和储氢机制。X射线衍射（XRD）分析结果表明，煅烧后的粉末以及经过10次充放电循环后的样品均具有正交结构。放电容量在第1次循环时达到最大值，在333 K时为530.3 mA·h·g⁻¹，且随温度升高而增加。放电容量在前3次循环期间明显下降，然后在298 K、313 K和333 K时分别稳定在约80 mA·h·g⁻¹、160 mA·h·g⁻¹和350 mA·h·g⁻¹。通过XRD、X射线光电子能谱（XPS）和质谱（MS）以及压力 - 成分 - 温度（PCT）方法研究了储氢机制。在充电过程中，氢原子可能嵌入氧化物晶格并形成均匀的固溶体。英国皇家版权所有（C）2009，由爱思唯尔有限公司出版。保留所有权利。