Free-standing 3D nitrogen-doped graphene/Co 4 N aerogels with ultrahigh sulfur loading for high volumetric energy density Li-S batteries

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 Co 4 N nanoparticles (3DNG-Co 4 N) 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 Co 4 N nanoparticles on polysulfides. The 3DNG-Co 4 N/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.