Sulfur nanocrystals anchored graphene composite with highly improved electrochemical performance for lithium–sulfur batteries

Self-assembled graphene/sulfur composite as high current discharge cathode for lithium-sulfur batteries

“…The cycle performance of the RGO/S composite at 0.5ma/cm 2 is shown in Figure 7(b). A discharge capacity of 865.1mAh g -1 is obtained for the RGO/S composite in the first discharge process, and still presents a capacity of 720mAh g -1 after 50 cycles, corresponding to a capacity loss of 16.8 %, which is much higher than that of the sulfur-graphene composite and graphene-wrapped sulfur particles [21,30], and comparable to sulfur nanocrystals/graphene composite [20], sulfur/three-dimensional graphene/MWCNT composite and 3D graphene/sulfur composite [31,32]. The coulombic efficiency of the RGO/S composite keeps steadily around 95% throughout the charge/discharge process, suggesting that the RGO/S composite offers not only high discharge current performance, but also good stability.…”

“…Graphene is favorable for its high surface area, good chemical stability and conductivity as one of the most promising conductive additives [17]. Recently, researchers have demonstrated that embedding sulfur in flexible reduced graphene oxide (RGO) sheets to form RGO/S anode materials promoted long cycle life of Li-S cell [18][19][20]. However, in order to guarantee the conductivity of S cathode for rate performance, the sulfur loading amount in these RGO/S composites is low and rarely reaches a high content level up to 80 wt.…”

Graphene-wrapped sulfur nanospheres with ultra-high sulfur loading for high energy density lithium–sulfur batteries

“…Table 1 lists the detailed comparison of the electrochemical performance versus sulfur and electrode for various sulfur/graphene composites [36][37][38][39][40][41][42]. The specific capacity versus the electrode is much higher than that of many sulfur/graphene composites [24,30,31,35,36,[40][41][42], but inferior than the ternary composites of graphene/sulfur coated by rGO [37] and sulfur/graphene/carbon nanotubes composite [38], and the uniformly dispersed sulfur on rGO [39]. Nevertheless, the results are quite satisfied considering the ultra-high sulfur loading.…”

“…Many pioneering work have reported that the use of conductive carbon matrix such as active carbon [19,20], mesoporous carbon [21], carbon nanotubes [22] and graphene [23,24], and conducting polymers including polypyrrole [25,26] and PANI [27][28][29] is one of the most promising strategies to resolve these problems.…”

“…The composite with 44.6% of sulfur exhibited an initial charge capacity of 1021 mA h g −1 and a reversible capacity of 657 mA h g −1 after 100 cycles. Our previous work demonstrated that the sulfur nanocrystal anchored graphene composite with 50% sulfur loading showed high and stable specific capacities up to 720 mA h g −1 over more than 100 cycles [24]. Though very high specific capacity versus sulfur was achieved in these composite, however, due to the poor conductivity of the active material, considerable weight of the electrode was occupied by the conductive additives, resulting in much lower gravimetric capacity of the material with respect to total mass of cathode (less than 300 mA h g −1 ).…”