Preparation And Store-Electrical Performance Of Porous Carbon With Template Method For Supercapacitor

As a new energy storage device, supercapacitor is widely used in the fields of military, transportation and communication due to its long cycle life, rapid charge-discharge, and wide operation temperature range. Porous carbons(PCs) and graphenes are widely used as electode materials owing to their large specific surface area, developed pore structure and high conductivity. In this paper, PCs and hollow spherical porous graphenes(HSPGs) were prepared from coal tar pitch(CTP) with template method. PCs and HSPGs were characterized by N2 adsorption/desorption, X-ray photoelectron spectroscopy, transmission electron microscope and field emission scanning electron microscope techniques. The electrochemical performance of PC and HSPG electrodes were investigated by using galvanostatic charge/discharge, cyclic voltammetry and electrochemical impedance spectroscopy. The main conclusions are as follows.PCs were prepared from CTP by potassium hydroxide(KOH) activation with iron nitrate nonahydrate(Fe(NO3)3?9H2O) as template. Under optimum conditions with the masses of CTP, Fe(NO3)3 ? 9H2 O, KOH at 4.2 g, 16.8 g, 6.0 g, the BET surface area(SBET), total pore volume(Vt), average pore size(Dap) and non-Vmic percent of PC(PC4.2-16.8-6) reaches 1683 m2/g, 2.07 cm3/g, 4.91 nm and 79.2%, respectively. The specific capacitance of PC4.2-16.8-6 electrode reaches 182 F/g at a current density of 0.05 A/g. The capacitance retention of PC4.2-16.8-6 was 81.6% at 20 A/g(an increase of current density by a factor of 400), showing an excellent rate performance. The energy density of PC4.2-16.8-6 supercapacitor reaches 15.72 Wh/kg in 1 M Et4NBF4 organic electrolyte.HSPGs were synthesized from CTP by one-step method in different atmosphere with magnesium oxide(MgO) as template coupled with KOH activation, of which the SBET and Vt is up to 1947 m2/g and 1.16 cm3/g, respectively. Under optimum conditions with the masses of CTP, MgO, KOH at 3 g, 18 g, 6 g in argon atmosphere, the Dap and SBET of HSPG3-18-6-Ar reaches 2.31 nm and 1871 m2/g, respectively. At 0.05 A/g, the specific capacitance of HSPG3-18-6-Ar electrode reaches 321 F/g, the specific capacitance retention matains 76.0% at 20 A/g, showing outstanding rate performance. The specific capacitance retention of HSPG3-18-6-Ar electrode after 1000 cycles matains 94.5%, exhibiting excellent cycle stability. The energy density of HSPG3-18-6-Ar supercapacitor reaches 11.11 Wh/kg, and it is 7.18 Wh/kg at a power density of 9502 W/kg.PCs were prepared from CTP by using calcium carbonate(CaCO3) as template and cetyl trimethyl ammonium bromide(CTAB) as surfactant. The electrochemical performance of PC electrodes was investigated in ionic liquid electrolyte. Under optimum conditions with the masses of CaCO3, CTP and CTAB at 13.50 g, 6.75 g, 6.75 g, the specific capacitance of PC2-1-1 electrode reaches 117 F/g, showing a high energy density of 64.18 Wh/kg. The energy density of PC2-1-1 supercapacitor remains 22.19 Wh/kg at an average power density of 4276 W/kg. The capacitance retention of PC2-1-1 electrode and the energy density retention of PC2-1-1 capacitor reach 92.2% and 90.0%, respectively, showing perfect cycle stability.