Metal organic frameworks templated sulfur-doped mesoporous carbons as anode materials for advanced sodium ion batteries

Abstract

In this paper, we focus on an innovative sulfur doping method with MOF-5 and inorganic sulfur powders as templated carbon precursor and sulfur source, in which sulfur powders were firstly encapsulated into the abundant pore structure of MOF-5 and then sulfur doping process could be realized through further pyrolysis treatment. Based on the results of material characterization, sulfur-doped mesoporous carbon (SPC) holds an amorphous structure with an enlarged interlayer distance of 0.386 nm and a mesoporous size distribution of 3–6 nm, while sulfur atoms existing in SPC (2.5 at.%) are mainly in the form of thiophene-type bonds (CSC and CS). Benefitting from the structural advantages, SPC electrode could display a long-term cycling stability with a reversible capacity of 173.7 mAh g−1 at 200 mA g−1 after 500 cycles and an outstanding rate capability of 104.9 and 90 mAh g−1 even the current raised up to 1.6 and 3.2 A g−1, respectively. The enhanced electrochemical performances could be mainly attributed to the introduction of S atoms into carbon structure, which can effectively enlarge the interlayer distance, improve the electronic conductivity and promote the insertion/extraction process of sodium storage.