Biomass-derived porous carbon modified glass fiber separator as polysulfide reservoir for Li-S batteries

By Selvan, Ramakrishnan Kalai; Zhu, Pei; Yan, Chaoi; Zhu, Jiadeng; Dirican, Mahmut; Shanmugavani, A.; Lee, Yun Sung; Zhang, Xiangwu
Published in Journal of Colloid and Interface Science 2018

Abstract

Biomass-derived porous carbon has been considered as a promising sulfur host material for lithium-sulfur batteries because of its high conductive nature and large porosity. The present study explored biomass-derived porous carbon as polysulfide reservoir to modify the surface of glass fiber (GF) separator. Two different carbons were prepared from Oak Tree fruit shells by carbonization with and without {KOH} activation. The {KOH} activated porous carbon (AC) provides a much higher surface area (796 m2 g?1) than pyrolized carbon (PC) (334 m2 g?1). The R factor value, calculated from the X-ray diffraction pattern, revealed that the activated porous carbon contains more single-layer sheets with a lower degree of graphitization. Raman spectra also confirmed the presence of sp3-hybridized carbon in the activated carbon structure. The {COH} functional group was identified through X-ray photoelectron spectroscopy for the polysulfide capture. Simple and straightforward coating of biomass-derived porous carbon onto the {GF} separator led to an improved electrochemical performance in Li-S cells. The Li-S cell assembled with porous carbon modified {GF} separator (ACGF) demonstrated an initial capacity of 1324 mAh g?1 at 0.2 C, which was 875 mAh g?1 for uncoated {GF} separator (calculated based on the 2nd cycle). Charge transfer resistance (Rct) values further confirmed the high ionic conductivity nature of porous carbon modified separators. Overall, the biomass-derived activated porous carbon can be considered as a promising alternative material for the polysulfide inhibition in Li

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