A three-dimensional interconnected nitrogen-doped graphene-like porous carbon-modified separator for high-performance Li-S batteries

Suppressing rapid capacity decay caused by the shuttle effect of dissolved lithium polysulfides between two electrodes is crucial to the realization of a practical lithium-sulfur (Li-S) batteries. Herein, the shuttle effect of polysulfides was efficiently inhibited by using a lightweight and thin functional separator in the form of coating three-dimensional interconnected nitrogen-doped graphene-like porous carbon nanosheets on one surface of a commercial polypropylene separator. This structure for a thin functional separator heightens the reversible capacity and cycle performance by doping nitrogen to chemically bond with polysulfides and the porous carbon layer to physically block polysulfides. As a result, the Li-S batteries based on the functional separators deliver an initial capacity of 1169.0 mA h g-1 at current rate of 1C and a substantial capacity of 845.3 mA h g-1 after 500 cycles, corresponding to a low capacity decay of only 0.055% per cycle. Even at a high rate of 3C, the batteries can still deliver a high reversible capacity of 743.6 mA h g-1 with good cycle performance.