Dual-protection of a graphene-sulfur composite by a compact graphene skin and an atomic layer deposited oxide coating for a lithium-sulfur battery

Abstract

A reduced graphene oxide (rGO)-sulfur composite aerogel with a compact self-assembled rGO skin was further modified by an atomic layer deposition (ALD) of ZnO or MgO layer, and used as a free-standing electrode material of a lithium-sulfur (Li-S) battery. The rGO skin and ALD-oxide coating worked as natural and artificial barriers to constrain the polysulfides within the cathode region. As a result, the Li-S battery based on this electrode material exhibited superior cycling stability, good rate capability and high coulombic efficiency. Furthermore, ALD-ZnO coating was tested for performance improvement and found to be more effective than ALD-MgO coating. The ZnO modified G-S electrode with 55 wt% sulfur loading delivered a maximum discharge capacity of 998 mA h g(-1) at a current density of 0.2 C. A high capacity of 846 mA h g(-1) was achieved after charging/discharging for 100 cycles with a coulombic efficiency of over 92%. In the case of using LiNO3 as a shuttle inhibitor, this electrode showed an initial discharge capacity of 796 mA h g(-1) and a capacity retention of 81% after 250 cycles at a current density of 1 C with an average coulombic efficiency higher than 99.7%.

Sulfur synchronously electrodeposited onto exfoliated graphene sheets as a cathode material for advanced lithium–sulfur batteries

“…[16][17][18][19][20] Shi et al 27 synthesized a binder-free reduced graphene oxide-sulfur composite aerogel with a self-assembled compact reduced graphene oxide skin by hydrothermal method, showing an initial discharge capacity of 796 mAh g −1 and capacity retention of 81% after 250 cycles. Yang et al 28 reported electrochemical assembly strategy to achieve ordered sulfur-graphene nanowalls. Inspired by the effective electrolytic exfoliation of graphite into graphene aggregates recently reported, 29−32 herein, we report a facile and novel strategy to synthesis graphene-sulfur composites (GSC) basing on a rational design of electrolytic exfoliation of graphite into graphene combined with in situ electrodeposition of sulfur as a one-pot reaction.…”

Lithium-Sulfur Battery

“…Such improved rate capability and cycle stability are attributed to the unique coaxial architecture of the nanocomposite, in which graphene and CNFs enable electrodes with improved electrical conductivity, better ability to trap soluble polysulfide intermediates and accommodate volume expansion/shrinkage of sulfur during cycling [68]. Gao et al reported a reduced graphene oxide-sulfur composite aerogel with a compact self-assembled graphene oxide skin as cathode materials for Li-S batteries [69]. This electrode was further modified by an atomic layer deposition of ZnO or MgO for a free-standing electrode to prevent the polysulfide shuttle (Fig.…”

Novel Non‐Carbon Sulfur Hosts Based on Strong Chemisorption for Lithium–Sulfur Batteries

“…Recently, metal oxides without solubility in most organic solvents have been extensively explored as excellent additives to combine with sulfur for improving the performance of Li–S batteries . Metal oxides with an oxygen anion in their structure provide a strong polar surface, which can afford abundant polar active sites for entrapment of polysulfide.…”