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

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 (2445 F g⁻¹ at 0.5 A g⁻¹) and superior rate capability (1644 F g⁻¹ and 1383 F g⁻¹ at 20 A g⁻¹ and 50 A g⁻¹, respectively), as well as satisfactory long-term endurance (∼93% capacitance retention after 10,000 cycles at 20 A g⁻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.