Ni0.85Se anchored on N-doped MoSe2 hybrids for long-life asymmetric supercapacitors

The layered molybdenum diselenide (MoSe2) is an ideal electrode material for supercapacitors. However, its widespread application is severely hampered due to low capacity, poor rate performance, and inferior cycling durability. Herein, the Ni0.85Se anchored on N-doped MoSe2 (Ni0.85Se/N-MoSe2) hybrids have been successfully produced using a facile hydrothermal route, in which formamide and water served as the mixed solvent. Compared to the Ni0.85Se or N-MoSe2, the specific capacity of Ni0.85Se/N-MoSe2 hybrids was substantially enhanced due to the cooperative effect between Ni0.85Se and N-doped MoSe2 as well as unique mesoporous architecture. The Ni0.85Se/N-MoSe2 hybrids could deliver 276.5 C g−1 at 250 mA g−1. Moreover, a Ni0.85Se/N-MoSe2//activated carbon (AC) asymmetric supercapacitor (Ni0.85Se/N-MoSe2//AC ASC) could offer 58.4 F g−1 at 500 mA g−1, and a considerable energy density of 20.8 Wh kg−1 at 200 W kg−1. Impressively, the Ni0.85Se/N-MoSe2//AC ASC demonstrated outstanding cyclic durability (105.1 % of initial capacity could be retained after 15,000 cycles at 1000 mA g−1). A Ni0.85Se/N-MoSe2//AC ASC device could drive a timer for about 15 min. Therefore, the Ni0.85Se/N-MoSe2 hybrid is a promising positive electrode material for ASCs.