Electrochemical Characteristics of Chemically Prepared Poly(3‐alkylthiophene)

Abstract

Electrochemical characteristics of chemically synthesized poly(3‐alkylthiophene) having various alkyl groups are investigated for use in secondary batteries as electrode active materials. Excellent characteristics, such as nearly 100% coulombic efficiency and fairly flat potential during discharge, are observed in constant‐current charge‐discharge tests for all of the poly(3‐alkylthiophene)s. Maximum doping levels as high as 49% are obtained for poly(3‐alkylthiophene), along with relatively high energy density. Coulombic efficiencies in charge‐discharge tests and apparent diffusion coefficients determined by chronoamperometry increase with number of the cycle. Such “break‐in” phenomena are attributed both to retention of dopant ion, even in the discharged polymers after several charge‐discharge cycles, and to structural changes caused by swelling of the polymers with electrolyte molecules during the first several electrochemical cycles.