Postprocessing of solution-cast polyaniline for enhanced electrochemical properties

Commercially available solutions of polyaniline (PANI) stabilized with dinonylnaphthalene sulfonic acid (DNNSA) offer a convenient means of forming PANI films via solution casting that are of interest for energy storage and other electrochemical applications. Here, we study the electrochemical charge storage properties of 200–400 nm thick PANI films cast from PANI-DNNSA solutions before and after postprocessing steps. As-cast PANI-DNNSA films exhibit a specific capacitance of <20 F/g at a 50 mV/s sweep rate, which increases to >300 F/g after p-toluene sulfonic acid:butanol (pTSA:BuOH) and dibromopropane (PrBr2) treatments. Crosslinked PANI also exhibits a 25% improvement in capacity retention over un-crosslinked PANI after 500 charge/discharge cycles. The capacity, energy, and power of postprocessed PANI films is examined in a symmetric coin cell device, and the utility of soluble PANI is demonstrated by coating planar and porous substrates using spin coating, drop casting, and dip coating techniques. These studies inform the use of PANI-DNNSA to fabricate high-capacity electrochemical devices.