Reduced graphene oxide modified with naphthoquinone for effective immobilization of polysulfides in high-performance Li-S batteries

Graphene-based materials are explored to be promising candidates for lithium-sulfur batteries based on their unique two-dimensional geometry structure and excellent electric conductivity. However, the inferior ability to confine polysulfides results in quick capacity fading and poor cycling stability of graphene-related electrode materials. Herein, small organic naphthoquinone (NQ) molecules with redox active properties are introduced to the reduced graphene oxide (rGO) as an advanced sulfur host to significantly prolong cycle life for Li-S batteries. The effective combination between small NQ organic molecules and rGO successfully leads to the conductive composite network, where the keto groups from NQ play the key role in promoting the chemical absorption of polysulfides/sulfur by forming the S O interaction. Notably, the NQ-rGO composite shows superior lithium polysulfides absorptivity with a sulfur loading of 65.3%. The S/NQ-rGO displays outstanding electrochemical performances for lithium-sulfur batteries, in terms of large reversible capacities with excellent cycling stability (936 mAh g−1 after 200 cycles at 0.1C and 670 mAh g−1 after 500 cycles at 1C) and superior rate ability (525 mAh g−1 at 5C).