Synthesis and capacitance properties of N-doped porous carbon / NiO composite materials

N-doped porous carbon / Ni is synthesized through pyrolysis,using coal-based polyaniline prepared by an in- situ polymerization approach as the carbon and nitrogen source,nickel acetate as the catalyst precursor. Next it is suc- cessfully transformed to N-doped porous carbon / NiO through a liquid-phase oxidation,which contains 0. 256% nitro- gen content and rich micro-mesopores. Its pore size is less than 40 nm,the microporous volume is 80. 4% ,the BET specific surface area is 452. 5 m2 / g,the BET average pore width is 1. 9 nm,and the BJH adsorption average pore di- ameter is 3. 5 nm. Among them,the porous carbon retains the aromatic nucleus of some coal macromolecules,its sur- face also has a certain amount of carboxyl and hydroxyl groups,and nitrogen element is mainly doped into the porous carbon in the form of pyridinic N and pyrrolic N. NiO particles about 100 nm diameter are embedded on the surface or in the pores of porous carbon. The as-synthesized N-doped porous carbon / NiO combines the electric double-layer ca- pacitance capacity of porous carbon and pesudocapacitance capacity of NiO. It has a high specific capacitance,good cycling stability and rate performance. Its specific capacitance is high to 541. 6 F / g at the current density of 1. 0 A / g. And it is reduced to 245. 8 F / g at 5. 0 A / g for 1 000-cycle charge-discharge tests and the capacitance retention is up to 85. 6% .