Regioregularity and Molecular Weight Effects in Redox-Active Poly(3-hexylthiophene)-block-poly(ethylene oxide) Electrode Binders

Simultaneous electron- and ion-conducting polymeric binders for battery electrodes offer a multifunctional alternative to commonly used poly(vinylidene fluoride). One example is poly(3-hexylthiophene)-block-poly(ethylene oxide) (P3HT-b-PEO), which conducts electrons and ions in the P3HT and PEO domains, respectively. Notably, P3HT stores charge by doping and dedoping, which further adds to the overall capacity of the battery electrode. Conjugated P3HT has been extensively studied for various solid state applications (e.g., photovoltaic cells, field-effect transistors, and light-emitting diodes), where the performance is strongly affected by regioregularity and molecular weight. However, in electrochemical systems such as in batteries, the effects of regioregularity and molecular weight on the charge storage performance are not understood for P3HT-b-PEO. Here, by comparing different P3HT-b-PEO block copolymers of varying P3HT regioregularity (86–97%) and molecular weight (8–19 kg mol–1), we demonstrate a s...