Nitrogen and iron codoped porous carbon polyhedra for effectively confining polysulfides and efficiently catalyzing their conversion in lithium–sulfur batteries. Issue 10 (24th August 2020)

• Record Type: Journal Article
• Authors: Yu, Jingping; Khan, Shahzad Ahmad; Zhao, Dengke; Li, Ligui; Wu, Zexing; Niu, Xiaojun; Chen, Shaowei
• Is Part Of: Sustainable energy & fuels. Volume 4:Issue 10(2020)
• Page Start: 5215
• Page End: 5222
• Publication Date: 2020-08-24
• Subjects: Renewable energy sources -- Periodicals; Fuel cells -- Periodicals; Electric batteries -- Periodicals; Electrochemistry -- Periodicals; 660.297
• DOI: 10.1039/d0se00942c
• Languages: English
• ISSNs: 2398-4902

Abstract

Abstract : Fe–N–C microporous carbon polyhedra with a trace amount of well-dispersed Fe atoms can effectively confine polysulfides and efficiently catalyze their conversion. Abstract : Effectively confining lithium polysulfides (LiPSs) and efficiently catalyzing their conversion represent a judicious approach to the preparation of high-rate, long lifespan lithium–sulfur (Li–S) batteries. Herein, an Fe-containing zeolitic imidazolate framework Fe-ZIF-8 is used as a precursor to synthesize a Fe–N–C polyhedron composite that shows a high specific surface area of 1459.3 m 2 g −1, a large pore volume of 1.037 cm 3 g −1 and a high nitrogen content of 7.29 at%. Benefiting from the high surface area and polarity of the carbon matrix, the Fe–N–C polyhedron composite can effectively adsorb and confine LiPSs. The S@Fe–N–C based electrode with a high sulfur loading of 72 wt% shows a high initial specific capacity of 1296 mA h g −1 at 0.1C and can retain a capacity of 450 mA h g −1 after 500 charge–discharge cycles at 1C, corresponding to a low fading rate of 0.068% per cycle. In contrast, a low capacity of 345 mA h g −1 is observed for the S@N–C reference electrode even after only 200 cycles. Moreover, the Fe–N x –C y sites within the S@Fe–N–C electrode can also efficiently catalyze the redox conversion of LiPSs during the charge–discharge process, leading to a much higher reversible capacity of 1178 mA h g −1 at 0.1C, as compared with the 626 mA h g −1 for the S@N–C electrode. These results support the approach to the preparation of N-doped porous carbons with catalytically active M–N x –C y (M is transition metal) sites for high-rate, long-lifespan sulfur cathodes for Li–S batteries.