NH_4PO_3-SiO_2复合电解质的溶胶凝胶法制备和导电性能

Electrical Performance of NH_4PO_3-SiO_2 Composite Electrolytes Prepared by a Sol-gel Method

用溶胶凝胶法制备了复合固体电解质xNH_4PO_3-SiO_2(x=1,2,4),并研究了该电解质在125￣250℃范围内的导电性能。复合电解质的相结构分析表明,NH_4PO_3和SiO_2在溶胶凝胶法制备过程中没有发生化学反应;复合电解质的电导率随着NH_4PO_3含量增大而提高,并与NH_4PO_3的形态相关。电导活化能随NH_4PO_3含量的上升而下降,表明在sol-gel法制备的复合电解质中,起电导作用的主要是NH_4PO_3,而SiO_2主要起支撑作用;另外SiO_2比表面积对电导率的影响不大,表明在这种复合质子导体中,基本上不存在电导的界面增强效应;电导率随着环境气氛中含水量的提高而提高,说明水在传导过程中起着重要作用。最后,根据上述现象提出了复合电解质的导电机理。

Proton-conductive composite electrolytes consisting of xNH4PO3-SiO2 （x=1,2,4） were synthesized by a solgel method. X-ray diffraction investigation showed that NH4DO3 was chemically stable in the process of sol-gel preparation. The conductivity of the resulted composites was measured with impedance spectroscopy. The conductivity was improved by increasing the molar ratio of NH4DO3. Meanwhile the activation energy for conductivity decreased with NH4DO3 content. This indicates that NH4DO3 is responsible for the high conductivity and SiO2 serves as a supporting matrix, although the conductivity was slightly affected by the size of SiO2 particles. The proton conductivity was dramatically enhanced by increasing the water content, indicating that the effect of water is significant.