Characterization of Electrochemical Capacity of a Biotemplated Polypyrrole Membrane

Recent studies of polypyrrole (PPy) electrodes have been increasing the interfacial surface area in order to increase electrochemical performance. We present a novel method of electropolymerizing PPy doped with dodecylbenzenesulfonate (DBS) referred to as biotemplating. A biotemplated conducting polymer utilizes phospholipid vesicles in order to form a three dimensional structure with a sponge-like shape. The vesicles, measuring 1–2 μm in diameter, are added in situ with the polymerization solution. They become enveloped while maintaining their structure during electropolymerization of PPy(DBS). The result of this structure is a significant increase in surface area compared to current techniques. There are several advantages in using biotemplated conducting polymers as battery electrodes. Compared to a planar PPy(DBS) membrane, biotemplated PPy(DBS) membranes have a roughly 50% increased storage capacity. There is an expected reduction in volumetric expansion during ion ingress/egress into the polymer backbone. This reduction would result in decreased fatigue loading and improving cyclability. Further, biotemplated PPy(DBS) membranes can be fabricated into thin structures with increased flexibility, allowing them to be rolled into various packaging sizes. In this article, the charge density of a biotemplated PPy(DBS) membrane as a function of charging and discharging currents is compared to a planar PPy(DBS) membrane. The structural enhancement offers systemic advantages by providing higher volumetric energy density and decreased fatigue loading for applications involving conducting polymer electrodes.