Electroactive Polymers as Battery Electrodes

J.L. Lutkenhaus
Texas A&M University,
United States

Keywords: electroactive polymers, batteries, capacitors, electrodes, V2O5, polyaniline

Summary:

Plastic power, or energy storage platforms primarily consisting of polymers, offers opportunities never before available in current state-of-the-art prismatic or coin cells, such as flexible, structural, or stretchable energy storage. Electroactive polymers, a class of polymers that undergoes reversible reduction and oxidation, are currently explored as electrodes in batteries and electrochemical capacitors. Used alone or as part of a hybrid electrode, electroactive polymers are rapidly growing in interest due to their redox activity, conductivity, synthetic versatility, and mechanical properties. This talk will first introduce how electroactive polymers operate, their specific challenges, and latest advances specifically in batteries. Several key challenges include doping level or capacity and electrochemical stability. This talk will then discuss recent work from my group that address these challenges. The design of ultra-stable polyanilines, which are reversibly stable up to 4.5 V vs. Li/Li+, will be presented. Stability results from synthesizing polyaniline in the presence of a strong polyacid that dopes the polyaniline. Perhaps one of the most interesting aspects of electroactive polymers is their adaptability to unconventional battery processing methods, such as spraying. Spray-on batteries are of potential interest for the area of structural energy storage, where a battery is seamlessly integrated into structural panels or other surfaces. This talk will highlight spray-on polyaniline nanofiber-graphene based cathodes evaluated against lithium metal anodes. Both polyaniline nanofibers and graphene oxide sheets are dispersed in water and then alternately sprayed onto a surface to build up an electrode in a layer-by-layer fashion. After reduction, the resulting electrode is highly porous and conductive. Another advantage of electroactive polymers is that they have the potential to impart unusual flexibility and toughness into otherwise brittle metal oxides in a hybrid electrode configuration. This talk will also present highly flexible and mechanically tough V2O5 hybrid electrodes, enabled by an electroactive block copolymer. The block copolymer contains ion-conducting poly(ethylene oxide) blocks and electron-conducting poly(3-hexylthiophene) blocks. The outlook for electroactive polymers is very promising with new advances in chemistry, processing, and composites. These may one day lead to ultra flexible or structural energy storage systems enabled by "plastic power".