Preparation, characterization and application of modified macroporous carbon with Co-N site for long-life lithium-sulfur battery

A modified macroporous carbon (mMPC) containing Co-N-x site is developed for sulfur retention to enhance cycleability of lithium-sulfur battery. Various nitrogen sites such as graphitic-N, pyrrolic-N, pyridinic-N, pyridinic-N oxide, and Co-N-x are created during macropore formation. The sites without Co show limited polysulfide (PS) adsorption capability because nucleophilic N absorbs PS species via the weak interaction between N and Li in N-Li-S bondage. The electrophilic Co(II) in Co-N-x absorbs PS species via a strong interaction between S and Co in S-Co bond. The dual interaction of Co-N-x site with S-Co and N-Li-S bondages significantly enhances the PS adsorption. The resultant Li-S battery with the mMPC shows excellent cycleability, exhibiting a very low capacity degradation rate of 0.25 mAh g(-1) per cycle after initial 20 cycles. A rate capacity as high as 660 mAh g(-1) has been achieved after 300 cycles at 1 C charge-discharge rate. (C) 2016 Elsevier B.V. All rights reserved.