Acetate anion-intercalated nickel-cobalt layered double hydroxide nanosheets supported on Ni foam for high-performance supercapacitors with excellent long-term cycling stability

Abstract

As a widely concerned material for supercapacitors, nickel cobalt layered double hydroxides (NiCo-LDHs) often suffer from the inferior rate capability and cycling stability due to the low electrical conductivity and easy agglomeration. To address these shortcomings, a simple in-situ hydrolysis approach is successfully developed to construct a binder-free system consisting of acetate anion-intercalated nickel cobalt layered double hydroxides (A-NiCo-LDHs) and Ni foam (NF) without additional alkali sources. The resulting A-NiCoLDH/NF electrodes exhibited obviously enhanced capacitive properties owing to the unique nanostructure and strong synergistic effects. It is worth noting that the optimized A-Ni5Co5-LDH/NF electrode delivered the highest performance among the electrodes studied, including ultrahigh specific capacitance (2445Fg−1 at 0.5Ag−1) and superior rate capability (1644Fg−1 and 1383Fg−1 at 20Ag−1 and 50Ag−1, respectively), as well as satisfactory long-term endurance (∼93% capacitance retention after 10,000 cycles at 20Ag−1). The attractive performances and facile fabrication make the A-Ni5Co5-LDH/NF system a promising candidate for low-cost high-performance energy storage devices.