Title: Co4N Nanosheets Assembled Mesoporous Sphere as a Matrix for Ultrahigh Sulfur Content Lithium−Sulfur Batteries

Author: Ding-Rong Deng, Fei Xue, Yue-Ju Jia, Jian-Chuan Ye, Cheng-Dong Bai, Ming-Sen Zheng, and Quan-Feng Dong

Abstract:
High utilization and loading of sulfur in cathode holds the key in realization of Li-S batteries. We here synthesized a Co4N mesoporous sphere, which was made up of nanosheets via an easy and convenient method. This new material presents high affinity, speedy trapping and absorbing capacity for polysulfides, and acts as a bifunctional catalysis for sulfur redox processes, therefore it is an ideal matrix for S active material. With such a mesoporous sphere used as a sulfur host in Li-S batteries, extraordinary electrochemistry performance has been achieved. With a sulfur content of 72.3 wt% in the composite, the Co4N@S delivered a high specific discharge capacity of 1659 mAh g-1 at 0.1 C, almost reaching its theoretic capacity. Also, the battery exhibited large reversible capacity about 1100 mAh g-1 at 0.5 C and 1000 mAh g-1 at 1 C after 100 cycles. At a high rate of 2 C and 5C, after 300 cycles, the discharge capacity finally stabilized at 805 mAh g-1 and 585 mAh g-1. Even at the 94.88% sulfur content, the cathode can still deliver an extremely high specific discharge capacity of 1259 mAh g-1 with good cycle performance.


                                    

Full Link: http://pubs.acs.org/doi/abs/10.1021/acsnano.7b01945