Dual-Functional Graphene Carbon as Polysulfide Trapper for High-Performance Lithium Sulfur Batteries

Abstract

The lithium sulfur (Li-S) battery has attracted much attention due to its high theoretical capacity and energy density. However, its cycling stability and rate performance urgently need to improve because of its shuttle effect. Herein, oxygen-doped carbon on the surface of reduced graphene oxide (labeled as ODC/rGO) was fabricated to modify the separators of Li-S batteries to limit the dissolution of the lithium polysulfides. The mesoporous structure in ODC/rGO can not only serve as the physical trapper, but also provide abundant channels for fast ion transfer, which is beneficial for effective confinement of the dissoluble intermediates and superior rate performance. Moreover, the oxygen-containing groups in ODC/rGO are able to act as chemical adsorption sites to immobilize the lithium polysulfides, suppressing their dissolution in electrolyte to enhance the utilization of sulfur cathode in Li-S batteries. As a result, because of the synergetic effects of physical adsorption and chemical interaction to immobilize the soluble polysulfides, the Li-S batteries with the ODC/rGO-coated separator exhibit excellent rate performance and good long-term cycling stability with 0.057% capacity decay per cycle at 1.0 C after 600 cycles.

Graphene/Carbon Black Co‐modified Separator as Polysulfides Trapper for Li‐S Batteries

“…So XPS is employed to investigate the surface chemical composition of rGO. The XPS survey spectrum of rGO (Figure S4a) displays two sharp peaks and one obscure peak at the binding energy of 284.8 eV, 534.0 eV and 164.2 eV, which are identified as the presence of C 1s (Figure S4b), O 1s (Figure S4c) and S 2p (Figure S4d), respectively ,, . Fitting the C 1s peak with a binding energy of 284.8, 286.2, 287.8, and 290.0 eV inferred to the presence of chemical bonds of C−C, C−O, C=O, and O‐C=O.…”

“…Compared with CB, CNTs, or the other traditional carbon materials, two dimensional graphene is more likely to form successive layers, which can efficiently inhibit the migration of polysulfides through steric hindrance . Furthermore, the polar oxygen‐containing groups, or heteroatoms doping of graphene provides chemical adsorption sites for immobilizing the lithium polysulfides, and suppressing the shuttle effect. Thus the utilization of sulfur is enhanced in Li−S batteries.…”

Single Atoms on Graphene for Energy Storage and Conversion

“…Therefore, the design of flexible substrates is necessary to load single atoms. Graphene with good mechanical stability is often used to fabricate flexible electrodes in supercapacitors or batteries . The conductive graphene skeleton can not only be beneficial for the fast electron transfer, but also relieve the large mechanical stress of electrodes derived from the H 2 bubbles in HER process.…”

Intertwined Nitrogen‐Doped Carbon Nanotube Microsphere as Polysulfide Grappler for High‐Performance Lithium‐Sulfur Batteries

“…Three peaks below 500 cm À 1 can be distinctly seen, which correspond to the characteristic peaks of the sulfur. [36] XRD diffraction patterns of sulfur, carbon nanotube microspheres and carbon nanotube microsphere/sulfur composites are shown in Figure 2b. [36] XRD diffraction patterns of sulfur, carbon nanotube microspheres and carbon nanotube microsphere/sulfur composites are shown in Figure 2b.…”

“…[36] XRD diffraction patterns of sulfur, carbon nanotube microspheres and carbon nanotube microsphere/sulfur composites are shown in Figure 2b. [36] The peak pattern of the SCNT/S spectrum indicates that the sulfur still appears in the crystalline form, but its peak intensity is weakened, indicating that the sulfur has successfully entered the internal pores of the carbon material. Among them, the high-intensity diffraction peaks at 23°and 27°are the characteristic diffraction peaks of sulfur, indicating that the sulfur has good crystallinity.…”