NiCoSe2/Ni3Se2 lamella arrays grown on N-doped graphene nanotubes with ultrahigh-rate capability and long-term cycling for asymmetric supercapacitor

In this paper, we report a one-step electrodeposited synthesis strategy for directly growing NiCoSe2/Ni3Se2 lamella arrays(LAs) on N-doped graphene nanotubes(N-GNTs) as advanced free-standing positive electrode for asymmetric supercapacitors. Benefiting from the synergetic contribution between the distinctive electroactive materials and the skeletons, the as-constructed N-GNTs@NiCoSe2/Ni3-Se2LAs present a specific capacitance of ~1308 F g^-1 at a current density of 1 A g^-1. More importantly, the hybrid electrode also reveals excellent rate capability(~1000 F g^-1 even at 100 A g^-1) and appealing cycling performance(~103.2% of capacitance retention over 10,000 cycles). Furthermore, an asymmetric supercapacitor is fabricated by using the obtained N-GNTs@NiCoSe2/Ni3Se2LAs and active carbon(AC) as the positive and negative electrodes respectively,which holds a high energy density of 42.8 W h kg^-1 at 2.6 k W kg^-1, and superior cycling stability of ~94.4% retention over 10,000 cycles. Accordingly, our fabrication technique and new insight herein can both widen design strategy of multicomponent composite electrode materials and promote the practical applications of the latest emerging transition metal selenides in next-generation high-performance supercapacitors.