Ionic conductivity in PEO-KOH polymer electrolytes and electrochemical cell performance

Polyethylene oxide (PEO) and potassium hydroxide (KOH) alkaline solid polymer electrolytes were prepared by the solution cast technique. The PEO: KOH wt%. ratio in the alkaline solid polymer electrolyte system which exhibits the highest room temperature conductivity is 60:40. The conductivity was 3.10 x 10(-5) S cm(-1). X-ray diffraction (XRD) and electrochemical impedance spectroscopy (EIS) were used to study the characteristics of the PEO polymer electrolyte films. The Rice and Roth model was used to evaluate the number density of charge carriers. Knowing the number density of charge carriers enabled the mobility and diffusion coefficient to be calculated. An all solid-state Ni(OH)(2)/MH rechargeable metal hydride cell has been fabricated using the highest conducting PEO-KOH alkaline solid polymer electrolyte. The cell was charged at a constant current of 2 mA and discharged at 0.5 mA. The discharge characteristics improved upon cycling and the plateau voltage maintained above 1.3 V for more than 2 hours during the 16(th) cycle. (c) 2005 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.