Polyaniline-coated selenium/carbon composites encapsulated in graphene as efficient cathodes for Li-Se batteries

In this work, we developed a polyaniline (PANI)-coated selenium/carbon nanocomposite encapsulated in graphene sheets (PANI@Se/C-G), with excellent performance in Li-Se batteries. The PANI@Se/C-G nanostructure presents attractive properties as cathode of Li-Se batteries, with a high specific capacity of 588.7 mAh·g–1 at a 0.2C (1C = 675 mA·g−1) rate after 200 cycles. Even at a high rate of 2C, a high capacity of 528.6 mAh·g–1 is obtained after 500 cycles. The excellent cycle stability and rate performance of the PANI@Se/C-G composite can be attributed to the synergistic combination of carbon black (as the conductive matrix for Se) and the double conductive layer comprising the uniform PANI shell and the graphene sheets, which effectively improves the utilization of selenium and significantly enhances the electronic conductivity of the whole electrode.