Ultra-high Rates and Reversible Capacity of Li-S Battery with a Nitrogen-doping Conductive Lewis Base Matrix

To improve the electrochemical performance of lithium sulfur batteries, a conductive Lewis base matrix, nitrogen doped graphene (NG), was prepared here through a facile strategy of annealing a polypyrrole/ reduced graphene oxide composite. The obtained NG was demonstrated with enriched pyridinic-N doping and was employed as the matrix of sulfur cathode with ultra-high rates, reversible capacity and high coulombic efficiency. The improved performance can be attributed to the high conductivity of the NG and the enhanced adsorption energy of Li2Sn (n=4-8) on the NG surface. The NG can act not only as an electronic conductive network but also as a Lewis base catalyst matrix that promotes the higher Li2Sn to be further oxidized completely to S-8 as demonstrated in the cyclic voltammetry curve, which can thus significantly improve the sulfur utilization and cyclic stability even at a high sulfur loading of 75% (w/w) in the S@NG composite. (C) 2016 Elsevier Ltd. All rights reserved.