Electrostatic self-assembly assisted hydrothermal synthesis of bimetallic NiCo2S4 @N, S co-doped graphene for high performance asymmetric supercapacitors

With high electrochemical activity and good energy storage performance, bimetallic pseudocapacitive materials of Ni-Co sulfides have been extensively and deeply researched. However, the low electrical conductivity, irreversible reduction reaction and structural instability significantly limit the practical application of bimetallic NiCo2S4. In this work, NiCo2S4 @N, S co-doped graphene (NCS-G) composite material with high electrochemical performance is prepared by an efficient chemical precipitation assisted hydrothermal method. As the ideal skeleton and excellent conductive network, N, S co-doped graphene could effectively improve the structural stability of the as-prepared NCS-G, thus increasing the utilization and efficient electron transfer of NCS. Notably, the NiCo2S4 could not only provide numerous reaction sites, but also avoid the re-stacking of graphene sheets. Owing to the above merits, the NCS-G(3) electrode exhibits a maximum specific capacitance of 1145 F g(-1) (at 0.5 A g(-1)). The rate performance of the electrode retains 91.7% at the current density of 10 A g(-1) compared with that of 0.5 A g(-1). Furthermore, consisting of the graphene anode and the NCS-G(3) cathode, the asymmetric SC device demonstrates the outstanding energy density of 33.8 Wh kg(-1) at the power density of 799.8 W kg(-1) and good cycling performance of 74.5% after 50 0 0 cycles at 2 A g(-1). The synthesis strategy exploited in this work endows the electrode with marvelous rate performance, providing a new pathway to engineer the promising electrode material and manufacture high-performance energy storage devices. (C)& nbsp;2021 Elsevier Ltd. All rights reserved.

Automated summary

In this study, a NiCo2S4 @N, S co-doped graphene (NCS-G) composite material with excellent electrochemical performance was prepared by an efficient chemical precipitation assisted hydrothermal method. The N, S co-doped graphene effectively improved the structural stability and conductivity of NCS-G, leading to enhanced utilization and efficient electron transfer of NCS. The NCS-G(3) electrode exhibited a maximum specific capacitance of 1145 F g(-1) and excellent rate performance.