The electrochemical characteristics of electric double layer capacitors composed of solid polymer electrolytes with different thicknesses were investigated. A solid polymer electrolyte membrane was fabricated using electrospun fibers through solvent-assisted or thermally induced compression molding. Through the solvent-assisted or thermally induced compression molding processes, the poly(acrylonitrile) (PAN) microfibers consolidated together by the interlocking of the fibers under compression. A solid polymer electrolyte membrane clearly exhibited a free-standing shape with a bending capability. The electrospun PAN non-woven fabric and electrolyte salt composites showed higher ionic conductivity (>10(-3) S cm(-1) at 298 K) and capacitance compared with the liquid organic electrolyte. The solid polymer electrolytes provided a 10.6% increase in the energy density, seemingly due to the decrease in the IR drop and increase in the capacitance. (C) 2012 Elsevier B.V. All rights reserved.