Caterpillar-like graphene confining sulfur by restacking effect for high performance lithium sulfur batteries

- Hierarchical and porous graphene as sulfur host was obtained from graphite.
- The graphene could effectively trap sulfur by the Van der waals restacking effect.
- The graphene/sulfur cathode exhibited high rate and stable cycling performance.

Lithium sulfur batteries, one of the most promising energy storage methodologies for emerging electric vehicles, suffer from poor long-term cycling stability due to the shuttle effect caused by the dissolution of high order polysulfides. To enhance the cycling stability of sulfur cathode for high-energy lithium sulfur batteries, it is very critical to mitigating the dissolution of polysulfides. In this work, a caterpillar-like and reconfigurable graphene was designed to serve as the sulfur host. The caterpillar-like graphene highly expanded in solution and tightly restacked in dry condition due to the van der Waals force. Elemental sulfur was trapped and confined inside the restacked graphene layers. High mass loading of 63.8% sulfur in graphene was achieved after the caterpillar-like graphene was dried at 155 °C. The graphene-sulfur electrode has a good rate performance of 708 mAh g−1 at 167.5 mA g−1, 582 mAh g−1 at 335 mA g−1, 470 mAh g−1 at 837.5 mA g−1, 400 mAh g−1 at 1675 mA g−1 and a stable cycling performance with small capacity decay of 0.16% per cycle over 200 cycles at 1675 mA g−1. Moreover, the underlying mechanism of the restacking effect of caterpillar-like graphene on immobilizing the soluble lithium polysulfides was studied by density functional theory (DFT), which clearly explained how the graphene immobilized the soluble lithium polysulfides by the restacking effect.

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