In-situ electrodeposited CoSe@NiS heterojunction with enhanced performance for supercapacitors.

Rational design of porous heterostructured electrode materials for high-performance supercapacitors remains a big challenge. Herein, we report the in situ synthesis of CoSe@NiS hybrid nanosheet arrays supported on carbon cloth (CC) substrate though an efficient two-step electrodeposition method. Compared with pure CoSe and NiS, the well-defined CoSe@NiS heterojunction possesses enriched active sites, improved electrical conductivity, and reduced ion diffusion resistance. Benefiting from its hierarchically porous nanostructure and the synergistic effect of CoSe and NiS, the as-synthesized CoSe@NiS electrode delivers a gravimetric capacitance (C)/volumetric capacitance (C) of 1644.1F g/3161.7F cm at 1 A g, outstanding rate capability of 60.7% capacitance retention at 20 A g, as well as good cycling performance of 87.8% capacitance retention after 5000 cycles. Additionally, a hybrid supercapacitor (HSC) device presents a maximum energy density (E) of 65.7 Wh kg at 696.2 W kg with 93.3% cyclic durability after 15,000 cycles. Thus, this work proposes a simple and effective strategy to fabricate porous heterojunctions as high-performance electrode materials for energy storage devices.