High performance composite solid polymer electrolyte systems for electrochemical cells

We report high performance composite solid polymer electrolytes for electrochemical cells with comprehensive properties in high mechanical strength and high ionic conductivity. The composite electrolytes consist of porous non-woven polymer filament substrates that are impregnated with high ion-conducting materials. To insure structural integrity, the non-woven polypropylene/polyethylene core-shell substrates are sulfonated to activate the surface. The high ion-conducting materials are prepared from poly(vinyl alcohol) with the incorporation of acrylic acid monomer and cross-linking agent. The results show well-balanced physical and electrochemical characteristics that warrant excellent battery discharge capacity and cell power density. The room temperature ionic conductivity is high at 0.16-0.21 S cm^-1, and the activation energy is low at 0.5 kJ mol^-1. The mechanical strength is improved to 12 MPa with good elongation at 58-62%. The anionic transport numbers (t^-) are in the range of 0.93-0.99 in 1 M KOH, 0.91-0.97 in 1 M NaOH, and 0.83-0.91 in 1 M LiOH, respectively. The cyclic voltammetric study indicates good stability with symmetric curves between the cathodic and anodic peaks. The fully solid-state metal-air fuel cells exhibit excellent discharge capacity of 1506 mAh and high anode utilization of 95.7%. The power density is achieved at 91 mW cm^-2.