石墨烯对La_(0.94)Mg_(0.06)Ni_(3.49)Co_(0.73)Mn_(0.12)Al_(0.20)储氢合金电化学性能的影响

为了提高La_(0.94)Mg_(0.06)Ni_(3.49)Co_(0.73)Mn_(0.12)Al_(0.20)储氢合金的电化学性能,利用石墨烯与储氢合金研磨混合来对其进行表面改性处理。采用X射线粉末衍射仪(XRD)和扫描电子显微镜(SEM)分析合金的相结构和表面形貌。结果表明:添加石墨烯后合金的相结构并没有发生改变,石墨烯包覆在了合金的表面,增大了合金的比表面积,提高了合金的电化学性能。当添加质量分数为5%的石墨烯时,电极的最大放电容量可达到380.6mAh/g,容量保持率S50从69.5%提高到71.1%。添加石墨烯后,交换电流密度、极限电流密度和腐蚀电位均变大、电化学反应阻抗降低,说明电极的动力学性能得到改善。

Effects of Graphene on Electrochemical Properties for La0.94Mg0.06Ni3.49Co0.73Mn0.12Al0.20 Hydrogen Storage Alloy

La0.94Mg0.06Ni3.49Co0.73Mn0.12Al0.20 hydrogen storage alloy was modified by grinding graphene and hydrogen storage alloy to improve its electrical chemical properties. The results obtained by Xray diffraction (XRD) and scanning electron microscope (SEM) show that the phase structure of the alloy does not change after adding graphene. Graphene coated on the surface of the alloy increases the surface area of the alloy from SEM, and the electrical chemical performance of alloy were improved. When adding a mass fraction of 5% of graphene, the maximum discharge capacity of the electrode increases to 380.6 mAh/g, and the alloy capacity retention rate increases from 69.5% to 71.1% after 50 charge/discharge cycles. Furthermore, the exchange current density, limiting current density, corrosion potential are improved, and electrochemical reaction impedance is reduced after adding graphene, which indicate that the kinetic property of alloy electrode is enhanced.