Nitrogen-Doped Graphene Quantum Dots: Sulfiphilic Additives for the High-Performance Li–S Cells

The lithium–sulfur cell is considered to be the most promising next-generation energy storage system. However, the practical use of Li–S batteries is hindered by several problems such as poor cycle retention, low Coulombic efficiency, low sulfur loading, and so forth. We herein for the first-time propose nitrogen-doped graphene quantum dots as the sulfiphilic additive for the advancement of Li–S cell performance. We carry out direct decoration of conducting additives and carbon cloth interlayers with graphene quantum dots and nitrogen-doped graphene quantum dots, which are evaluated in Li–S cells. Nitrogen-doped graphene quantum dots exhibit strong sulfiphilic properties, and therefore, they anchor the liquid-phase polysulfides. The Li–S cell using the nitrogen-doped graphene quantum dot-decorated carbon cloth interlayer shows a discharge capacity of 1454.4 mA h gS–1 at 0.1 C and a capacity retention of 98.2% at 0.5 C after 300 cycles even with a sulfur loading of 6.0 mg S cm–2. Our study demonstrates that the nitrogen-doped graphene quantum dot is a promising additive, which can improve the viability of Li–S cells for the next generation of energy storage systems.