Flexible self-supporting interconnected cobalt sulfide nanosheets enable high-loading and long-cycling Li-S batteries with high areal capacity

Abstract

Lithium-sulfur batteries (LSB) with high theoretical specific capacity/energy density still face some practical challenges, for instance shuttle effect and sluggish redox kinetics, which leads to rapid capacity decay. To overcome these challenges, herein, a porous and flexible sulfur host composed of interconnected Co9S8 nanosheets grown on carbon cloth was constructed. The interconnected carbon fiber skeleton and porous conductive Co9S8 nanosheets can not only provide abundant electron/ion-transport channels, but also offer adequate void to accommodate volume expansion of sulfur, thus ensuring high sulfur utilization and remarkable cycle stability of electrode. Meanwhile, the abundant adsorption and catalytic sites provided by Co9S8 nanosheets can effectively inhibit dissolution of polysulfides and improve conversion kinetics of polysulfides, effectively suppressing “shuttle effect”. The Co9S8-CC/Li2S6 electrode achieves high discharge capacity (1315.1 mAh g−1, 0.1C), excellent rate capability (872.4 mAh g−1, 2C) and outstanding cyclic stability (decay of 0.02 %/cycle over 1500 cycles, 2C).

Keywords

• Co9S8 nanosheet
• Self-supporting sulfur host
• Strong adsorption ability
• Highly-efficient electrocatalysis