The covalent grafting of polypyrrole to a carbon backbone via electrochemically aided atom transfer radical polymerization (eATRP) technique for supercapacitor applications

Abstract

Capacitors are devices that store energy by way of electric field. Supercapacitors, capacitors that can store between 10 and 100 times more energy than electrolytic capacitors but function at lower voltage limits, are of particular interest as they can accept and deliver charge at a quicker rate and can tolerate many more charge/discharge cycles than batteries. These supercapacitors have garnered particular interest over the last decade. This is perhaps unsurprising as we look to move away from large clunky energy storage devices and toward lightweight, durable, and efficient ways of storing and moving our energy. In order to create an effective supercapacitor, a synthetic pathway employing electrochemically mediated atom transfer radical polymerization was designed to covalently attach polypyrrole (PPy) to a carbon-based capacitive backbone. Products were then converted into an ink and grafted onto screen printed electrodes for electrochemical testing. The final product displayed a capacitance of 173.6 F/g, a 46.5% increase over pure PPy. After simultaneous 0.6, 0.7, 0.8, and 1.0 V degradation tests, the product maintained 82% retention of capacitance, more than double the retention of pure PPy. Charging times and total system resistivity remained low, as expected for supercapacitive materials.