Science: The storage capacity of a supercapacitor is limited by the surface area of the electrodes and by the electrodes' ability to absorb and release electrons. Research on redox-active materials focuses on the latter problem, but the materials are fragile and not particularly porous so have a low surface area. Two years ago, William Dichtel of Cornell University and his colleagues created a highly porous crystal, called a covalent organic framework (COF), that is also redox-active, but it did not have the conductivity necessary to be commercializable. Now they have revealed that coating their COF with a conductive polymer increased the capacitance from 160 F/g to 350 F/g, higher than any commercial supercapacitor. Because the materials used in Dichtel's device are readily available, they have much more promise for commercial use than harder-to-create carbon-nanotube capacitors.
