Chemisorption of polysulfides through redox reactions with organic molecules for lithium\u2013sulfur batteries

Ge Li,Zhongwei Chen,Aiping Yu,Yifei Yuan,Xiaolei Wang,Min Ho Seo,Shun Wang,Jun Lu,Matthew Li,Lu Ma,Tianpin Wu

doi:10.1038/s41467-018-03116-z

Abstract

Lithium–sulfur battery possesses high energy density but suffers from severe capacity fading due to the dissolution of lithium polysulfides. Novel design and mechanisms to encapsulate lithium polysulfides are greatly desired by high-performance lithium–sulfur batteries towards practical applications. Herein, we report a strategy of utilizing anthraquinone, a natural abundant organic molecule, to suppress dissolution and diffusion of polysulfides species through redox reactions during cycling. The keto groups of anthraquinone play a critical role in forming strong Lewis acid-based chemical bonding. This mechanism leads to a long cycling stability of sulfur-based electrodes. With a high sulfur content of ~73%, a low capacity decay of 0.019% per cycle for 300 cycles and retention of 81.7% over 500 cycles at 0.5 C rate can be achieved. This finding and understanding paves an alternative avenue for the future design of sulfur–based cathodes toward the practical application of lithium–sulfur batteries.

Highlights

Lithium–sulfur battery possesses high energy density but suffers from severe capacity fading due to the dissolution of lithium polysulfides
The assynthesized composites (S-AQ-G) were achieved by attaching AQ to reduced graphene oxide (rGO) through π–π stacking between the anthracene ring layers[32], followed by the addition of S forming the homogeneous composites (Fig. 1a)
The existence of AQ and rGO with enhanced density of electron clouds effectively changes the status and activity of S34,35, which is revealed by the differential scanning calorimetry (DSC) result (Supplementary Fig. 1) with lower endothermic peak at around 120 oC

Summary

Introduction

Lithium–sulfur battery possesses high energy density but suffers from severe capacity fading due to the dissolution of lithium polysulfides. Significant amount of the transition metal hydroxides/oxides/sulfides has to be used to provide efficient “sulfiphilic” surface, which significantly reduces the total energy of the S electrodes In this context, it is still highly desired to design novel trapping materials and to develop new mechanisms to enable enduring Li–S redox chemistry[25]. We demonstrate, for the first time to the best of our knowledge, a novel strategy to develop highly stable S electrodes by utilizing commercially available or natural abundant organic small molecules with redox catalytic properties Such organic molecules are capable of suppressing dissolution and diffusion of polysulfides species through redox reactions during cycling

Methods

Results

Conclusion