Preparation and properties of PVA/PAAK alkaline polymer electrolytes for nickel-metal hydride batteries

Poly(vinyl alcohol)/potassium polyacrylate poly(acrylic acid)(PVA/PAAK) alkaline polymer electrolyte were prepared by solution casting method and alkaline solution activating. The alkaline polymer electrolyte were characterized by alternating current(AC) impedance method, cyclic voltammetry (CV) and XRD. The influence of PAAK on the ionic conductivity of polymer electrolyte was analyzed. The results indicate that PAAK can make the polymer electrolyte system containing more KOH solution. On the other hand, the addition of PAAK decreases the crystallinity of PVA, and the results to the improvement of ionic conductivity of polymer electrolyte. The PVA/PAAK alkaline polymer electrolyte exhibits a good electrochemical performance with a highest ionic conductivity of 3.074×10^-2 S/cm at ambient temperature and electrochemical stable window of 2.2 V. Polymer metal hydride (MH)-Ni battery was assembled successfully using the PVA/PAAK alkaline polymer electrolyte and Mg-based hydrogen storage alloy as the negative electrode. It is shown that the polymer MH-Ni battery has a better cycle life than the conventional MH-Ni battery.