Article ID Journal Published Year Pages File Type
1646255 Materials Letters 2012 4 Pages PDF
Abstract

Expanded mesocarbon microbeads (EMCMB) are prepared by oxidizing pristine mesocarbon microbeads (MCMB). The d002 value calculated from X-ray diffraction results shows that the average interlayer distance of MCMB increases after oxidizing modification. The increased interlayer distance facilitates Li+ insertion kinetics, which causes an extraordinarily improved capacity of EMCMB (100 mAh g−1) at −40 °C, compared with pristine MCMB (almost no capacity at −40 °C). The facilitated Li+ insertion kinetics is analyzed by electrochemical impedance spectroscopy (EIS). EIS results demonstrate that both charge-transfer resistance and Li+ diffusion resistance of the EMCMB decrease obviously. The diffusion coefficients of Li+ in MCMB and EMCMB at −40 °C calculated from EIS are 2.46×10−17 cm2 s−1 and 1×10−15 cm2 s−1, respectively.

► Modifying commercial mesocarbon microbeads (MCMB) by oxidization expanding. ► An excellent capacity of 100 mAh g−1 at −40 °C. ► Smaller charge-transfer resistance and better Li+ diffusion kinetics at low temperature.

Related Topics
Physical Sciences and Engineering Materials Science Nanotechnology
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