Construction of NiCoMo electrode with unanticipated strong cyclic stability by transition from oxide into layered double hydroxide

Supercapacitors with high energy density ( E ) and cyclic stability is urgent for the irrepressible expanding in energy storage field. Multicomponent NiCo-based layered double hydroxides (LDH) are rapidly developed as positive electrode materials. By utilizing the good conductivity of Mo alloying element as reactive site, ternary components of NiCoMo compounds are developed, which endow a superior specific supercapacitance ( C ) and good stability. After addition of Mo element, the phase structure transforms from NiCo 2 O 4 oxide into NiCo LDH, and morphology from sea-urchin-like microsphere into nanorod with raising Mo content. The obtained positive electrode material of Ni 1 Co 2 Mo 0.5 microspheres with nanosheets folded on the surface exhibits an excellent electrochemical performance with a C of 5960 F g −1 at 1 A g −1 , much exceeding the 1250 F g −1 of NiCoO 4 . The assembled asymmetric supercapacitance of Ni 1 Co 2 Mo 0.5 //active carbon (AC) device has an E of 52.3 Wh kg −1 at a P of 697 W kg −1 , and a capacity retention rate of 92.5 % after 15000 cycles at a large charging current density of 10 A g −1 , revealing a high E and excellent cycling stability. The transitions of phase structure and morphology induced by Mo addition eventuate the good supercapacitance performance, and this ternary compound could be served as positive electrode material for supercapacitors in long-time working fields. • Mo-modified NiCo electrode materials are constructed. • Ni 1 Co 2 Mo 0.5 electrode shows a superior capacity of 5960 F g −1 at 1 A g −1 . • An excellent cycling stability is gained of 92.5 % after 15000 cycles at 10 A g −1 . • Active sites by Mo addition enhance the supercapacitance.