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13 results on '"Chiang, A.S.T."'

6. Preparation of ordered mesoporous aluminosilicate using carbon mesoporous materials as template

Author

Shing-Jong Huang, Ayyamperumal Sakthivel, Tae-Wan Kim, Chiang A.S.T., K Chen, Wen-Hua Chen, Ryong Ryoo, and S.B. Liu

Subjects
Mesoporous organosilica, Materials science, Chemical engineering, chemistry, Aluminosilicate, Inorganic chemistry, chemistry.chemical_element, Mesoporous material, Molecular sieve, Zeolite, Carbon
Abstract

A novel method for preparing ordered replicated mesoporous-microporous composite materials (RMM) using carbon mesoporous molecular sieves as template is reported. In particular, the novel aluminosilicate material (RMM-1), synthesized by replication of carbon mesoporous molecular sieve CMK-1 using ZSM-5 zeolite precursor, is found to possess a structure analogous to MCM-48 molecular sieve.

Published
2004
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10. Preformed Boehmite Nanoparticles As Coating Materials for Long-Cycling LiCoO2.

Author

Fey, G. T. K., Weng, Z. X., Chen, J. G., Lu, C. Z., Kumar, T. P., Naik, S. P., Chiang, A.S.T., Lee, D.C., and Lin, J. R.

Subjects
HYDROXIDE minerals, BOEHMITE, CATHODES, NANOPARTICLES, BAUXITE, VOLTAMMETRY
Abstract

A simple mechano-thermal coating procedure for the production of long-cycling LiCoO2 is described. Preformed nanoparticulate boehmite was used as the coating material. The coating procedure resulted in the cathode particles covered in a 20-30 nm thick kernel of boehmite, as revealed by TEM examination. XRD studies showed that the lattice parameter c diminished upon coating, indicating that a substitutional compound of the composition LixAlyCo1-yO2 may have formed upon calcination. SEM images, R-factor values from XRD studies and galvanostatic charge-discharge studies showed that a coating level of 1.0 wt % gave an optimal performance in capacity and cyclability. SEM images showed that above the 1.0 wt % coating level, the excess boehmite adhered to the coated cathode particles as sperules. ESCA depth profile analysis showed partial diffusion of aluminum from the surface to the interior. Galvanostatic cycling studies showed that at a coating level of 1.0 wt %, cyclability improved three- and twelve-fold for the two commercial LiCoO2 samples tested. Cyclic voltammetry revealed that the hexagonal-monoclinic-hexagonal phase transformations during cycling were suppressed in the coated cathode materials. [ABSTRACT FROM AUTHOR]

Published
2004
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13. Preformed Boehmite Nanoparticles As Coating Materials for Long-Cycling LiCoO2.

Author

Fey, G. T. K., Weng, Z. X., Chen, J. G., Lu, C. Z., Kumar, T. P., Naik, S. P., Chiang, A.S.T., Lee, D.C., and Lin, J. R.

Subjects
*HYDROXIDE minerals, *BOEHMITE, *CATHODES, *NANOPARTICLES, *BAUXITE, *VOLTAMMETRY
Abstract

A simple mechano-thermal coating procedure for the production of long-cycling LiCoO2 is described. Preformed nanoparticulate boehmite was used as the coating material. The coating procedure resulted in the cathode particles covered in a 20-30 nm thick kernel of boehmite, as revealed by TEM examination. XRD studies showed that the lattice parameter c diminished upon coating, indicating that a substitutional compound of the composition LixAlyCo1-yO2 may have formed upon calcination. SEM images, R-factor values from XRD studies and galvanostatic charge-discharge studies showed that a coating level of 1.0 wt % gave an optimal performance in capacity and cyclability. SEM images showed that above the 1.0 wt % coating level, the excess boehmite adhered to the coated cathode particles as sperules. ESCA depth profile analysis showed partial diffusion of aluminum from the surface to the interior. Galvanostatic cycling studies showed that at a coating level of 1.0 wt %, cyclability improved three- and twelve-fold for the two commercial LiCoO2 samples tested. Cyclic voltammetry revealed that the hexagonal-monoclinic-hexagonal phase transformations during cycling were suppressed in the coated cathode materials. [ABSTRACT FROM AUTHOR]

Published
2004
Full Text
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