All-solid electrochemical capacitors (EC) utilizing a proton conducting polymer electrolyte and graphite electrodes have demonstrated exceptionally high rate capability. The solid polymer electrolyte-based ECs charge and discharge at sweep rate over 20 V s(-1) and exhibit a time constant of 10 ms. This high rate performance is enabled by a proton conducting ternary solid thin film electrolyte composed of silicotungstic acid. orthophosphoric acid, and polyvinyl alcohol. This work shows that solid polymer electrolytes can support high power and high rate energy storage applications. (C) 2011 Elsevier B.V. All rights reserved.