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

Abstract

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.

Promoting the application of sulfur electrodes in lithium sulfur batteries: a review about the optimization

“…The average capacity degradation rate is just 0.12%, and this remains the case even after 300 cycles [20]. Researchers Park et al look into the possibility of using graphene and nitrogen-doped graphene quantum dots as conductive additives and as an intermediary layer of carbon fabric [21]. They observe that a Li-S cell had a discharge capacity of 1454.4 mAh g -1 when measured at 0.5C after the cell is used [21].…”

“…Researchers Park et al look into the possibility of using graphene and nitrogen-doped graphene quantum dots as conductive additives and as an intermediary layer of carbon fabric [21]. They observe that a Li-S cell had a discharge capacity of 1454.4 mAh g -1 when measured at 0.5C after the cell is used [21]. With a sulfur concentration of 6.0 mg S cm -2 , it is possible to keep the capacity at 98.2% even after numerous cycles have been completed (Fig.…”

Advanced cathodic free-standing interlayers for lithium–sulfur batteries: understanding, fabrication, and modification

“…Wang et al and Park et al also obtained a nitrogen doping interlayer in the ammonia flow, while Saroha et al used urea to introduce nitrogen into the interlayer. [72][73][74] ALD is also a good method to dope-specific atoms into the freestanding interlayer. Lin et al prepared CNT@SACo interlayers by heating a Co-containing precursor at 100 1C, as shown in Fig.…”

Computational screening of functionalized MXenes to catalyze the solid and non-solid conversion reactions in cathodes of lithium–sulfur batteries

“…To address these issues suffered by S electrodes, one of the most favorable strategies is employing conductive matrixes to load sulfur particles, such as several polar and nonpolar carbonaceous structures, 5,[16][17][18][19][20] transition-metal carbides, [21][22][23][24][25][26] transition-metal oxides, [27][28][29][30][31] transition-metal nitrides, [32][33][34][35][36] and transition-metal sulfides, [37][38][39] based on their confinement abilities for polysulfides through physical and chemical interactions. The composited electrodes can usually improve the electronic conductivity, relaxing the volume expansion during the conversion processes from sulfur to Li 2 S and anchoring the mobile polysulfides to some extent.…”