2D-on-2D Al-Doped NiCo LDH Nanosheet Arrays for Fabricating High-Energy-Density, Wide Voltage Window, and...

Battery-type electrode materials with high capacity, wide potential windows, and good cyclic stability are crucial to breaking through energy storage limitations and achieving high energy density. Herein, a novel 2D-on-2D Al-doped NiCo layered double hydroxide (NiCoAl_x LDH) nanosheet arrays with high-mass-loading are grown on a carbon cloth (CC) substrate via a two-step hydro/solvothermal deposition strategy, and the effect of Al doping is employed to modify the deposition behavior, hierarchical morphology, phase stability, and multi-metallic synergistic effect. The optimized NiCoAl_0.1 LDH electrode exhibits capacities of 5.43, 6.52, and 7.25 C cm^-2 (9.87, 10.88, and 11.15 F cm^-2) under 0-0.55, 0-0.60, and 0-0.65 V potential windows, respectively, illustrating clearly the importance of the wide potential window. The differentiated deposition strategy reduces the leaching level of Al³⁺ cations in alkaline solutions, ensuring excellent cyclic performance (108% capacity retention after 40 000 cycles). The as-assembled NiCoAl_0.1 LDH//activated carbon cloth (ACC) hybrid supercapacitor delivers 3.11 C cm^-2 at 0-2.0 V, a large energy density of 0.84 mWh cm^-2 at a power density of 10.00 mW cm^-2, and excellent cyclic stability with ≈135% capacity retention after 150 000 cycles.