Abstract
The poor cycle stability and low volumetric energy density of lithium-sulfur (Li-S) batteries caused by the shuttle effect of polysulfides and low density of sulfur cathode restrict their practical application. Composite materials of ultra-light carbon and polar metal compounds are usually used as sulfur host materials, but they can lead to the low volumetric energy density of resulting Li-S batteries. Herein a lightweight 3D free-standing aerogel consisting of N-doped reduced graphene oxide modified by Co4N nanoparticles (3DNG-Co4N) are designed and synthesized, making full use of the superior electrical conductivity of the 3D network structure and the excellent adsorption capacity and catalytic activity of Co4N nanoparticles on polysulfides. The 3DNG-Co4N/S cathodes with ultrahigh sulfur loading of 24.0 mg cm?2 pressed at 20 MPa achieves a high areal capacity of 21.8 mAh cm?2 and volumetric energy density of 2678.1 Wh L?1 at 2.0 mA cm?2 with an electrolyte/sulfur ratio as low as 3.3 μL mg?1, which are among the best results in Li-S batteries. This work provides an effective strategy to design high volumetric energy density Li-S batteries with high sulfur loading.
NSTL