Graphene-Based Hierarchically Micro/Mesoporous Nanocomposites as Sulfur Immobilizers for High-Performance Lithium–Sulfur Batteries

Abstract

Herein, a hierarchically micro/mesoporous nanocomposite of graphene and carbon nanospheres (HGC) is used as an immobilizer for a lithium−sulfur (Li−S) battery with enhanced performance. HGC derived from graphene oxides and polyvinylidene fluoride polymers, combined with the advantages of graphene and porous carbon nanospheres, exhibits a hierarchically micro/ mesoporous structure with an ultralarge specific surface area of up to 3182 m 2 g −1 and a large pore volume of 1.91 cm 3 g −1 . Graphene as a conducting network can enhance electronic conductivity, while porous nanospheres like a reservoir can effectively store and immobilize sulfur particles. HGC/sulfur electrode material obtained via a melting infusion process exhibits high reversible specific capacity of 1250 mA h g −1 with a high sulfur content of 74.5 wt %, and it still has a capacity of 916 mA h g −1 after 100 cycles, which is better than that of pristine porous graphene and carbon nanospheres. Furthermore, the relative capacity decay of the HGC/sulfur electrode is only 0.005 and 0.004% per cycle at 2 C and 4 C, respectively, after 450 charge/discharge cycles, exhibiting remarkable performance in terms of long-term electrochemical stability.

Flexible Solid‐State Supercapacitors with Enhanced Performance from Hierarchically Graphene Nanocomposite Electrodes and Ionic Liquid Incorporated Gel Polymer Electrolyte

“…(3) The rational hierarchically micro/mesoporous structure contributes a lot in improving the capacitive performance. Micropores in the electrode materials offer a quite large specific surface area (2416 m 2 g −1 ), acting as an ion reservoir ensuring the charge storage capability, while the abundant mesopores offer large ions transport channel that facilitates the ion transportation rapidly at high current density …”

Yolk–Shell Structured Assembly of Bamboo‐Like Nitrogen‐Doped Carbon Nanotubes Embedded with Co Nanocrystals and Their Application as Cathode Material for Li–S Batteries

“…Lithium–sulfur batteries incorporate elemental sulfur, which is inexpensive, naturally abundant, and environmentally benign, and are considered to be a promising system for next‐generation energy‐storage systems . However, the low electrical conductivity of elemental sulfur and the discharge products and dissolution of polysulfides during cycling must be overcome to improve the cycling and rate performances of Li–S batteries .…”

A N-doped graphene–cobalt nickel sulfide aerogel as a sulfur host for lithium–sulfur batteries

“…5,6 However, the development of lithium-sulfur batteries is still hampered by many challenges, which mainly stem from the sulfur cathode. 7 The rst main issue is that the inherent electronic insulation of elemental sulfur and its discharge nal product, Li 2 S 2 /Li 2 S, limit the utilization of active materials and the high rate performance of batteries. 7,8 The second major problem is the shuttle effect, which results in performance degradation of the Li-S batteries.…”

“…7 The rst main issue is that the inherent electronic insulation of elemental sulfur and its discharge nal product, Li 2 S 2 /Li 2 S, limit the utilization of active materials and the high rate performance of batteries. 7,8 The second major problem is the shuttle effect, which results in performance degradation of the Li-S batteries. On the one hand, soluble lithium polysulde intermediates (LiPSs, Li 2 S x , 4 # x # 8) are produced during the charge-discharge process, which increase the viscosity of the electrolyte and decrease the conductivity of the ions.…”