Highly improved electrochemical performance of Li-S batteries with heavily nitrogen-doped three-dimensional porous graphene interlayers

•Freestanding nitrogen-doped graphene functional interlayers have been prepared.•Functional interlayers can increase electron transport pathway and suppress shuttle effect.•Electrochemical performance of Li-S battery is greatly improved.•The Li-S cell delivers a high reversible capacity of 956 mAh g−1 after 50 cycles.

A freestanding nitrogen-doped graphene functional interlayer placed between the sulfur cathode and the separator has been investigated to enhance the electrochemical performance for lithium-sulfur (Li-S) batteries. The interlayer with three-dimensional porous structure and abundant of N-doping active sites, not only can increase electron transport pathway and the storage capacity of liquid electrolyte, but also can physically and chemically adsorb the highly soluble lithium polysulfides to reduce the loss of active material. With a pure sulfur electrode (high sulfur content of 70 wt%), the as-assembled Li-S battery delivers a high initial discharge capacity up to 1481 mAh g−1 at a rate of 0.1C, and maintains a reversible capacity of 956 mAh g−1 after 50 cycles of charge/discharge. Comparing with conventional cells, we have highly improved the electrochemical performance for Li-S batteries.

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