Construction of hairbrush-like (Ni3S2/NiSe-3:1)/carboxymethylcellulose derived carbon heterostructure as high-performance electrodes for supercapacitors

Nickel sulfides and nickel selenides have been widely explored as electrodes for supercapacitors (SCs) due to their high theoretical capacitances and low cost. However, the poor electrical conductivity and sluggish ion transport hinder their widespread applications in SCs. Herein, a series of (Ni3S2/NiSe-3:1)/carboxymethylcel-lulose derived carbon, (Ni3S2/NiSe-3:1)/CMC-C, heterostructures are built by one-step vulcanization, seleniza-tion and carbonization using Ni(OH)2/CMC-C as the precursor. By tuning the mass ratio of sulfur to selenium, one unique hairbrush-like (Ni3S2/NiSe-3:1)/CMC-C heterostructure with uniform nanorod arrays is formed, which exposes substantial redox active sites. The optimal (Ni3S2/NiSe-3:1)/CMC-C electrode displays high specific capacitance of 2005.1 F g-1 (842.1 mAh g-1) at 7 A g-1 and 1075.1 F g-1 (451.5 mAh g-1) at 35 A g-1. Furthermore, asymmetric supercapacitors (ASCs) with the (Ni3S2/NiSe-3:1)/CMC-C as anode and activated carbon (AC) as cathode are assembled and evaluated. The ASCs exhibit an energy density of 41.9 Wh kg-1 at a power density of 709.8 W kg-1 and reasonable cycling stability (77.5% retention, 10,000 cycles), indicating that the (Ni3S2/NiSe-3:1)/CMC-C electrode has broad application prospects in SCs and related energy applications.