Statistical design to optimize specific charges in polypyrrole by electrosynthesis

A design of experiments was employed to optimize the conditions of synthesi s in order to electrogenerate thick polypyrrole films suitable for applicat ion as a cathode in polymeric batteries or supercapacitors. The influence o f five main variables: potential of polymerization, generation time, monome r concentration, electrolyte concentration, and temperature, and their seco nd-order interaction on the specific charge were studied and optimized thro ugh three stages. The initial stage requires the synthesis of 16 films (des ign matrix). Every film is weighed and checked in the background solution t o obtain the stored charge and the specific charge. The resulting statistic al significance shows that optimization only is possible at low potentials. In a second stage a design matrix with eight new experiments allowed the d etermination of the variables of synthesis affecting the specific charge an d the direction of change of those variables to optimize this property. By changing the conditions of synthesis in that direction three more experimen ts resulted in a designed film 0.5 mu m thick and 104 Ah kg-l (C) 1999 The Electrochemical Society. S0013-4651(99)01-102-7. All rights reserved.