Nanoporous glassy carbon - A new electrode material for supercapacitors I. Effect of curing temperature on its structure and properties

Glassy carbon (GC) has high conductivity and good mechanical properties, but is costly due to the long preparation cycle and cannot be activated monolithically due to its extremely low penetrability. Therefore, it is impossible for GC to be used as electrode materials for electrochemical capacitors. A novel porous GC with a nanostructure with a shortened production route has been prepared. A hardening agent was added to a phenolic novalac resin, which was cured at temperatures below 250?℃. The cured resin was then crushed, ground, compacted to a disc, heated quickly to carbonization temperature and activated in flowing CO2, leading to the formation of monolithic nanoporous GC with a high capacity due to its large surface area, and high power density due to its good conductivity and proper pore structure. The key factor, the hardening temperature, which affects performance of electrochemical capacitors, is discussed in this paper. It is shown that the porosity of the carbonized resin increases with the hardening temperature, allowing the activation agent to diffuse inward and enhancing pore formation in the activation reaction. The structure of this nanoporous GC is between those of GC and activated carbon. Furthermore, the higher the hardening temperature, the more developed the pore structure. The products have a favorable pore structure and electrochemical performance when cured at temperatures above 225?℃.