孔结构对热电池用氧化镁吸附性能的影响

采用沉淀法制备用于热电池电解质流动抑制剂的氧化镁粉末, 通过调节氨水与镁盐的比例得到不同孔结构的粉末，采用XRD、SEM、TEM、FT-IR和N₂吸附-脱附等方法分析粉末的形貌和孔结构，研究孔结构对电解质漏液率和热电池性能的影响.结果表明:沉淀剂比例能显著改变孔结构，当n(NH₃·H₂O):n(Mg2+)=1.5: 1时，形成大量的介孔，比孔容提高到0.179 cm3/g，比表面积达到30.91 m2/g，氧化镁含量（质量分数）为35 %的电解质粘合板中漏液率仅为6 mg/cm2.适合吸附LiCl-KCl共晶盐的氧化镁孔径应在2~200 nm之间.电解质漏液率高导致热电池平均工作时间变短，氧化镁孔径过小会增加热电池平均激活时间. 

Effect of pore structure on adsorption properties of magnesium oxide in thermal battery

In this paper, MgO powder was prepared by precipitation for thermal battery. By adjusting the ratio of precipitating agent, MgO powder of different pore structure was obtained. Through X-ray diffraction(XRD), scanning electron microscopy(SEM),transmission electron microscope (TEM), nitrogen adsorption-desorption, and fourier transform infrared spectroscopy(FT-IR), the microstructure and pore structure of the powder were analyzed. The correlation between the pore structure and electrolyte leakage and electric properties of thermal battery were discussed in details. The results show that: the ratio of precipitating agent can significantly alter the pore structure; when the molar ratio of ammonia and magnesium salt is 1.5: 1, it forms a large number of mesopores.The pore volume is 0.179 cm3/g and the surface area is 30.91 m2/g.When the amount of MgO powder exceeds 35 %(mass fraction), the electrolyte leakage of the separators is only 6 mg/cm2.While the electrolyte is a kind of eutectic salt (LiCl-KCl), the pore size of MgO powder should be between 2~200 nm.High electrolyte leakage leads to a shorter average working time of thermal batteries.When the pore size of magnesium oxide is too small, it will increase the average activation time of thermal batteries.