LaNi_(4.25)Al_(0.75)包覆多孔SiO_2的改性及其电化学性能

Modification and electrochemical properties of LaNi_(4.25)Al_(0.75) coated with porous SiO_2

以正硅酸乙酯为原料,采用溶胶-凝胶法制备多孔SiO2凝胶,将LaNi4.25Al0.75合金粉与凝胶混合在500℃进行真空烧结。将真空烧结所得样品在吸氢系统中进行吸、放氢性能测试,用恒流电池测试仪研究其电化学性能。研究结果表明:所得样品的抗氧化性能明显比纯LaNi4.25Al0.75合金粉的抗氧化性能强,在常温下吸氢后暴露在空气中没有出现自燃现象;所得样品在吸、放氢测试中表现出良好的稳定性能,当以1C放电到0.9 V时,经30次充、放电循环后,纯LaNi4.25Al0.75合金的初始容量为270 mA.h/g,容量衰减27.8%;包覆多孔SiO2凝胶后其初始放电容量为260 mA.h/g,容量仅衰减7.5%。

The SiO2 gel was prepared through hydrolysis and condensation polymerization of tetraethyl orthosilicate and H20. The gel and LaNi4.25Al0.75 powders were mixed completely and heated at 500 ℃ for 2 h to obtain samples. The absorption hydrogen property of sample was tested at 0.5 MPa in H2. The constant current batteries tester was used to characterize the electrochemical properties of obtained samples. The results show that the sample after absorbing H2 does not self-ignite in atmosphere at normal temperature and has excellent combustion resistance property. The obtained samples have stable absorption/desorption hydrogen properties, and the initial discharge capacities of pure LaNi4.25A10.75 and obtained sample are 270 mA.h/g and 260 mA.h/g, and then decrease by 27.8% and 7.5% after 30 charge/discharge cycles to 0.9 V at 1 C, respectively.