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Structural Design of Polymer‐Derived Si OC Ceramic Aerogels for High‐Rate Li Ion Storage Applications
Author(s) -
Vallachira Warriam Sasikumar Pradeep,
Zera Emanuele,
GraczykZajac Magdalena,
Riedel Ralf,
Soraru Gian Domenico
Publication year - 2016
Publication title -
journal of the american ceramic society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.9
H-Index - 196
eISSN - 1551-2916
pISSN - 0002-7820
DOI - 10.1111/jace.14323
Subject(s) - aerogel , cyclohexane , materials science , pyrolysis , ceramic , acetone , chemical engineering , porosity , specific surface area , solvent , microstructure , polymer , bet theory , divinylbenzene , pyrolytic carbon , carbon fibers , catalysis , composite material , organic chemistry , chemistry , composite number , copolymer , styrene , engineering
Si OC ceramic aerogels with different porosity, pore size, and specific surface area have been synthesized through the polymer‐derived ceramic route by modifying the synthesis parameters and the pyrolysis steps. Preceramic aerogels are prepared by cross‐linking a linear polysiloxane with divinylbenzene ( DVB ) via hydrosilylation reaction in the presence of a Pt catalyst under highly diluted conditions. Acetone and cyclohexane are used as solvent in our study. Wet gels are subsequently supercritically dried with CO 2 to get the final preceramic aerogels. The Si OC ceramic aerogels are obtained after a pyrolysis treatment at 900°C in two different atmospheres: pure Ar and H 2 (3%)/Ar mixtures. The nature of the solvent has a profound influence of the aerogel microstructure in terms of porosity, pore size, and specific surface area. Synthesized Si OC ceramic aerogels have similar chemical compositions irrespective of processing conditions with ~40 wt% of free carbon distributed within remaining mixed Si OC matrix. The BET surface areas range from 215 m 2 /g for acetone samples to 80 m 2 /g for samples derived from cyclohexane solvent. The electrochemical characterization reveals a high specific reversible capacity of more than 900 mAh/g at a charging rate of C (360 mA/g) along with a good cycling stability. Samples pyrolyzed in H 2 /Ar atmosphere show a high reversible capacity of 200 mAh/g even at a high charging/discharging rate of 20 C. Initial capacities were recovered after whole cycling procedure indicating their structural stabilities resisting any kind of exfoliations.