Conducting Block Copolymer Binders for Carbon-Free Hybrid Vanadium Pentoxide Cathodes with Enhanced Performance

Polymeric binders are essential to battery electrodes, mechanically stabilizing the active materials. Most often, these binders are insulating, and conductive carbons must be added to the electrode structure. Conductive polymer binders, those that transport both ions and electrons, are of primary interest because they potentially eliminate the need for carbon additives. However, it is challenging to incorporate both ion- and electron-conductive polymeric binders into electrode systems because of differences in physical affinities among the two polymer types and the electroactive material. Here, we investigate amphiphilic polymeric binders comprised of electron- and ion-conducting poly(3-hexylthiophene)-block-poly(ethylene oxide) (P3HT-b-PEO) as compared to P3HT, PEO, and a blend of P3HT/PEO homopolymers in carbon-free V2O5 cathodes. The electrode with P3HT-b-PEO binder has the highest capacity of 190 mAh/g, whereas V2O5 is only 77 mAh/g at a C rate of 0.1 after over 200 cycles: a 2.5-fold improvement. Sim...