3D reticulate CoxNi3−xS2 nanostructure on nickel foam as a new type of electroactive material for high-performance supercapacitors

Abstract

3D reticulate Co_xNi_3−xS₂ nanostructures were grown on nickel foam using a simple precursor sulfuration route. Compared with monometallic Ni₃S₂, the introduction of an appropriate content of Co could markedly improve electrochemical properties. Also, the electrochemical performance of as-prepared Co_xNi_3−xS₂ nanostructures could be tuned by the Co content added to the Ni₃S₂. The investigation showed that 3D Co_xNi_3−xS₂ nanostructures prepared from the system with initial Co²⁺/Ni²⁺ molar ratio of 2/1 (labeled as S2/1) exhibited the best energy storage properties. At a current density of 2 mA cm⁻², the areal capacitance of S2/1 reached 3030 mF cm⁻²; and even at a current density of 30 mA cm⁻², the areal capacitance reached 2268 mF cm⁻¹. After 6500 cycles at a current density of 5 mA cm⁻², the capacitance retention retained 92.8% of the initial value, exhibiting excellent cycling stability. After 3D reticulate S2/1 nanostructures were fabricated into an asymmetrical supercapacitor with activated carbon, the energy density achieved 73.5 W h kg⁻¹ at a power density of 600 W kg⁻¹; and at high power density of 3024.06 W kg⁻¹, the energy density could still reach 50.04 W h kg⁻¹, which presents potential applications for energy storage as a high performance electrode material.