Fabricating three-dimensional hierarchical porous N-doped graphene by a tunable assembly method for interlayer assisted lithium-sulfur batteries

The high energy lithium-sulfur batteries have received more attention for next-generation energy storage; however, low conductivity of the sulfur cathode and shuttle of polysulfides still limit the utilization of sulfur. To optimizing sulfur utilization and improving the cycling lifespan of Li-S cells, we report a three-dimensional hierarchical porous N-doped graphene (NG) assisted sulfur cathode and its coated separator for high performance of Li-S batteries. In particular, the formation of the novel 3D structure is inspired from the combination of active hydrothermal releasing gas and cohesive action from in situ polymerization of pyrrole. The as prepared 3D N-doped graphene/S composite containing 75 wt% sulfur delivers reversible capacity of 582.7 mAh g (1) after 200 cycles at 0.2 C with capacity retention rate of 79.5%. The as-developed 3D N-doped graphene coated on separator as an interlayer could not only enhance the charge-transfer network of cathode but also protect the Li anode from been destroyed. The interlayer cell confirmed enhanced the cycling performance with reversible capacity of 851.8 mAh g (1) after 200 cycles at 0.2 C and retain 88.7% of its maximum discharging capacity (666.8 mAh g (1)) after 300 cycles at 0.5 C, suggesting potential strategy to tackle the fundamental challenges underlying high sulfur loading Li-S batteries. (C)2017 Elsevier B.V. All rights reserved.