Assembly of micro-/meso-/macroporous carbon optimized for Li-S batteries

A team of researchers from the School of Materials Science and Engineering and School of Electronic Science and Applied Physics at Hefei University of Technology demostrated that pore size distribution substantially influences the performances of cathode rather than specific surface area and total pore volume. Furthermore, an optimized assembly of micro/meso/macroporous carbon enables cathode present greatly improved electrochemical performances, in which micropore-volume-ratio to the total pore volume dominates cycling stability of batteries, meso/macropore-volume-ratio influences spaces for sulfur loading and channels to ion transfer.

This research provides a direction of fabricating porous materials for energy storage.The report appears in the latest issue of the journal NANO.

Based on the traditional S/C cathode, the effects of surface area, total pore volume and pore size distribution of carbon pores on performances of Li-S batteries are compared. In addition, on the premise of identically high sulfur content, the relation of the micro/meso/macropore volume ratio with the capacity, voltage plateau, rate capability, and cycle stability of Li-S battery are investigated. Among the samples, the porous carbon possesses the largest micropore volume ratio of 47.54% while a medium specific surface area of 1217 m2/g and inferior total pore volume of 0.54 cm3/g presents the highest initial discharge specific capacity of 1327 mAh/g and retention of 630 mAh/g over 100 cycles at 0.2C rate along with the best rate capability. The conclusions in this study can be directly applied in material fabrication for other systems of energy storage and even as criteria for further modification of Li-S batteries based on carbon material.