采用溶胶凝胶法,结合相转移法和碱液活化法制备了PVA/SiO2碱性微孔聚合物电解质,通过SEM、XRD、交流阻抗法和循环伏安法表征了电解质的结构与电化学性能.研究表明,PVA/5ωSiO2(ω为质量分数)共混膜上的微孔大小合适,聚合物电解质的离子电导率最大可达1.62×10-2 S cm-1,电化学稳定窗口2 V以上;将PVA/SiO2碱性微孔电解质组装成聚合物镁基镍氢电池,与传统镍氢电池相比,循环稳定性大大增加.
New poly(vinyl alcohol)/silica(designated as PVA/SiO2) alkaline micro-porous polymer electrolytes(AMPEs) were prepared by soaking PVA/SiO2 micro-porous composite membranes,obtained by solution casting of PVA/PEG/SiO2 membrane in acetone solution,into an electrolyte solution of 6 mol/L KOH aqueous solution.The morphology and structure of PVA/SiO2 composite polymer membranes were characterized by scanning electron microscopy(SEM) and X-Ray diffraction(XRD).The SEM photographs showed that the nano-SiO2 filler content was a crucial issue for the well-dispersed and optimal-sized pores which could storage charge carrier durably.Meanwhile,the crystalline of PVA decreased effectively for a large number of crystal defects and free volume appeared in the interface of inorganic particles and polymer for the addition of nano-SiO2 filler.The electrochemical properties of the AMPEs were measured by the alternating current impedance(AC impedance) and the cyclic voltammetry(CV) techniques.The results indicated that the PVA/SiO2 AMPEs containing 5 ω nano-SiO2 filler exhibited good performances at room temperature,such as 1.62×10-2 S cm-1 for ionic conductivity and 2.20 V for electrochemical stability window.What’s more,we used the gravimetric method to obtain the electrolyte uptake of various PVA/SiO2 composite micro-porous polymer membranes.From the data,we learned that the maximum electrolyte uptake could reach to 102.7% and it had very relevance to the size of pores in PVA/SiO2 composite polymer membranes,and then influenced the ionic conductivity.Each polymer Ni-MH battery was assembled by three parts: the new AMPE,Mg-based hydrogen storage alloy and the commercial sintered Ni(OH)2/NiOOH electrode,in which each part did for electrolyte and diaphragm,negative electrode and positive electrode,respectively.The cycle experiments of the batteries exhibited a high first-cycle discharge capacity of 613 mAh g-1 and stable discharge capacities about 330 mAh g-1 for the following 5 cycles.The resul