Graphitic nanofibers decorated with Ni3S2 interlaced nanosheets as efficient binder-free cathodes for hybrid supercapacitors

Abstract In this current work, we successfully decorated free-standing conductive functionalized graphitic nanofibers (GNFs) with interlaced Ni3S2 nanosheets (designated as GNFs@Ni3S2) by using a facile pulse-reversal deposition technique, and employed the GNFs@Ni3S2 composite as an efficient binder-free cathode material for hybrid supercapacitors (HSCs) for the first time. According to the results of the material characterizations, it confirmed that that surface of the GNFs was evenly deposited with Ni3S2 nanosheets, and the resultant composite was in fibrous nanostructure. On the basis of the series of electrochemical measurements, the GNFs@Ni3S2 composite electrode revealed almost three times larger discharge capacity than the pristine Ni3S2 electrode, and exhibited superior rate capability. Moreover, a HSC device based on the GNFs@Ni3S2 cathode delivered an impressive specific capacity of 34.6 mAh g−1 at 1 A g−1 and the maximum energy density of 44.2 Wh kg−1 at a power density of 1.2 kW kg−1. Most importantly, the HSC retained 68.9% of its initial capacity after 5000 consecutive charge/discharge cycles at a current density of 4 A g−1. The remarkable electrochemical performance of the binder-free GNFs@Ni3S2 composite electrode makes it to be regarded as one of the potential cathode materials for high-performance HSCs.