Preparation of high-performance activated carbons for electric

double layer capacitors by KOH activation of mesophase pitches

Mei-xian Wanga, Cheng-yang Wanga, Ming-ming Chena,

Yan-su Wanga, Zhi-qiang Shia, Xuan Dua, Tong-qi Lib, Zi-jun Hub

a Key Laboratory for Green Chemical Technology of MOE, School of

Chemical Engineering and Technology, Tianjin University, Tianjin

300072, Chinab National Key Laboratory of Advanced Functional Composite Materials,

Aerospace Research Institute of Materials & Processing Technology,

Beijing 100076, China

Two kinds of mesophase pitches with different softening

points were prepared at different soaking times and directly acti-

vated with KOH to study the effects of the softening point on the

textural characteristics of the resulting activated carbons and

their behavior as electrodes in capacitors. Results show that the

softening points of the two mesophase pitches are 280 and

330 �C, and the specific surface areas of the activated carbons

are 1337 and 1300 m2 g�1, respectively. The specific capacitance

of the higher softening point mesophase pitch-derived carbon is

higher (255.6 F g�1) than that of the lower softening point meso-

phase pitch-derived carbon (190.8 F g�1) at the same current den-

sity. Cyclic voltammograms show that the lower softening point

mesophase pitch-derived carbon exhibits better rectangular-

shaped i–V curves. The softening points of the mesophase pitches

prepared from even the same precursor can significantly affect the

electrochemical performance of the resulting activated carbons.

[New Carbon Mater 2010;25(4):285–90]

doi:10.1016/j.carbon.2010.08.018

Functionization of carbon nanotubes by plasma and the forma-

tion of their composites with polyaniline

Jie Zhanga,b, Jun-he Yangb, Run-ping Jiac, Xia Wangb, Jie Huanga

a College of Chemical Engineering, East China University of Science and

Technology, Shanghai 200237, Chinab School of Materials Science and Technology, University of Shanghai for

Science and Technology, Shanghai 200093, Chinac Department of Material Engineering, Shanghai Institute of Technology,

Shanghai 200233, China

Carbon nanotubes (CNTs) were modified by Ar plasma fol-

lowed by O2 etching in a plasma assisted chemical vapor deposi-

tion apparatus. The modified CNTs were polymerized with aniline

in a HCl aqueous solution to produce CNT/polyaniline compos-

ites. The CNTs modified by the plasma have a higher conductivity

(2.86 S/cm) than those modified by acid oxidation (0.936 S/cm).

The optimum plasma parameters were power (50 W), system

pressure (0.08 torr), treatment time (5 min), temperature

(110 �C), distance between two electrodes (5 cm) and current of

magnetic loop (0.8 A). SEM results revealed that the smooth sur-

face of the CNTs became rough after the plasma modification

and the diameters increased by about 80 nm. FTIR, Raman and

XRD all revealed the presence of polyaniline on CNT surfaces.

[New Carbon Mater 2010;25(4):291–6]

doi:10.1016/j.carbon.2010.08.019

Pyrocarbon transition layer and microstructure of mesophase

pitch based carbon/carbon fiber composites

Hao Liua,b, Ke-zhi Lia, He-jun Lia, Jin-hua Lua, Yan-qiang Zhaia

a School of Materials Science, Northwestern Polytechnical University,

Xi’an 710072, Chinab School of Chemistry and Chemical Engineering, Yulin University,

Yulin 719000, China

The microstructure of 2D PAN carbon fiber-reinforced meso-

phase pitch-based matrix carbon/carbon(C/C) composites having

a pyrocarbon transition layer was studied by polarized light

microscopy (PLM), scanning electron microscopy (SEM) and trans-

mission electron microscopy (TEM). PLM results indicate that the

matrix consisted of pyrocarbon and mesophase pitch carbon,

whose structure is anisotropic. TEM and SEM results show that

multilayer interfaces are formed inside the composite. The car-

bon fiber–pyrocarbon interface is generally continuous, with a

high degree of perfection and graphitic crystallites oriented paral-

lel to the interface. The interface between the mesophase pitch

carbon and the pyrocarbon is amorphous and is micro-fissured.

The size and the degree of orientation of the graphitic crystallites

gradually increase and the alignment of lattice fringes is gradu-

ally ordered from carbon fibers, to pyrocarbon to mesophase pitch

carbon. The mesophase pitch matrix is lamellar carbon oriented

parallel to the fiber axis. Numerous micro-cracks parallel to the

carbon fiber axis are formed within the partially bonded interface

and the matrix.

[New Carbon Mater 2010;25(4):297–302]

doi:10.1016/j.carbon.2010.08.020

Effect of pre-oxidation on microcracks in graphite foams

Juan Li, Can Wang, Cui-cui Zhang, Liang Zhan, Wen-ming Qiao,

Xiao-yi Liang, Li-Cheng Ling

State Key Laboratory of Chemical Engineering, East China University of

Science and Technology, Shanghai 200237, China

The formation mechanisms of microcracks in graphite foams

were investigated by varying the pre-oxidation temperature of the

precursor mesophase pitch. Results indicated that after the

mesophase pitch was pre-oxidized, its quinoline-insoluble com-

ponent became the dominant fraction, which leads to a decrease

in heat stress gradient and as a result, a decrease in the amount,

length and width of microcracks.

[New Carbon Mater 2010;25(4):303–7]

doi:10.1016/j.carbon.2010.08.021

Stability of multi-wall carbon nanotubes in air

Shuang-mei Zhua, Jun-qing Lia, Jin-hui Pangb, Hua-shun Zhangb,

Er-jun Liangb

a Department of Mathematics and Physics, College of Henan Engineering,

Zhengzhou 450052, Chinab Laboratory of Material Physics, Zhengzhou University, Zhengzhou

450052, China

354 CARBON 49 (2011) 352– 355