An interwoven carbon nanotubes/cerium dioxide electrocatalyst accelerating the conversion kinetics of lithium sulfide toward high-performance lithium-sulfur batteries

Abstract

Rechargeable lithium-sulfur (Li-S) batteries with environmental friendliness, low price, high specific capacity and energy density could be promising alternatives to a larger scope of energy storage in the near future. However, the practical application is impeded by the intrinsic insulation of sulfur and the fatal shuttle effect during the (dis)charging process. Herein, we report a strategy to address the drawbacks of Li-S batteries by inserting an interwoven carbon nanotubes/cerium dioxide electrocatalyst interlayer material (CNTs@CeO2) between the sulfur cathode and the separator. In the CNTs@CeO2 composite, the conductive network interwoven by CNTs facilitates electron transportation, and the abundant active sites in CeO2 cavities ensuring the adsorption-catalytic conversion of lithium polysulfides as well as the hollow structure of CeO2 is conducive to rapid electrolyte penetration and lithium ion migration. Benefiting from such multifunction, the battery with a CNTs@CeO2 interlayer exhibits superior rate performance, delivering a high discharge specific capacity of 1040.6 mAh g−1 at 0.2C and 652.5 mAh g−1 at 4C, respectively. Moreover, the battery shows excellent cycling stability with a capacity decay rate of 0.064% per cycle at 1C over 1000 cycles. These promising results demonstrate the potential application of CeO2-based electrocatalysts for high energy density Li-S batteries.