Large Capacity Enhancement of Carbon Electrodes by Solution Processing for High Density Energy Storage

An inexpensive, solution phase modification of flat carbon electrodes by electrochemical reactions of a 1,8-diaminonaphthalene derivative results in a 120 to 700-fold increase in capacity by formation of a 15-22 nm thick organic film. Modification of high surface area carbon electrodes with the same protocol resulted in a 12 to 82-fold increase in capacity. The modification layer contains 9-15% nitrogen present as –NH– redox centers that result in a large Faradaic component involving one H+ ion for each electron. The electrodes showed no capacity loss after prolonged cycling in 0.1 M H2SO4, and exhibited significantly higher charge density than similar reported electrodes based on graphene and polyaniline. Investigation of the deposition conditions revealed that N-doped oligomeric ribbons are formed both by diazonium ion reduction and diaminonaphthalene oxidation, and the 1,8 isomer is essential for the large capacity increases. The capacity increase has at least three contributions: increased microscopic...