Promoting Reversible Redox Kinetics by Separator Architectures Based on CoS 2 /HPGC Interlayer as Efficient Polysulfide‐Trapping Shield for Li–S Batteries

• Published in: Small (Weinheim an der Bergstrasse, Germany) Germany), 2020-08, Vol.16 (34)
• Main Authors: Hu, Qianqian, Lu, Jiqun, Yang, Chun, Zhang, Congcong, Hu, Jinlong, Chang, Shiyong, Dong, Haiyong, Wu, Chunyu, Hong, Ye, Zhang, Lingzhi
• Format: Article
• Language: English
• ISSN: 1613-6810; 1613-6829
• DOI: 10.1002/smll.202002046

Main obstacles from the shuttle effect and slow conversion rate of soluble polysulfide compromise the sulfur utilization and cycling life for lithium sulfur (Li–S) batteries. In pursuit of a practically viable high performance Li–S battery, a separator configuration (CoS 2 /HPGC/interlayer) as efficient polysulfide trapping barrier is reported. This configuration endows great advantages, particularly enhanced conductivity, promoted polysulfide trapping capability, accelerated sulfur electrochemistry, when using the functional interlayer for Li–S cells. Attributed to the above merits, such cell shows excellent cyclability, with a capacity of 846 mAh g −1 after 250 cycles corresponding to a high capacity retention of 80.2% at 0.2 C, and 519 mAh g −1 after 500 cycles at 1C (1C = 1675 mA g −1 ). In addition, the optimized separator exhibits a high initial areal capacity of 4.293 mAh cm −2 at 0.1C. Moreover, with CoS 2 /HPGC/interlayer, the sulfur cell enables a low self‐discharge rate with a very high capacity retention of 97.1%. This work presents a structural engineering of the separator toward suppressing the dissolution of soluble Li 2 Sn moieties and simultaneously promoting the sulfur conversion kinetics, thus achieving durable and high capacity Li–S batteries.