Controlled preparation of Ni–Al LDH–NO3 by a dual-anion intercalating process for supercapacitors

Ni–Al layered double hydroxide with nitrate anions as interlayer building blocks was synthesized by a dual-anion intercalating strategy of hydroxyl and nitrate anions during a facile co-precipitation process. In this case, nitrate anions with low charge densities are capable to expand the interplanar spacing between host layers of Ni–Al layered double hydroxide in the replacement of pristine carbonate anions, benefiting to the diffusion of electrolyte ions to active sites within electrodes. Moreover, the optimization for packed arrangement of Ni–Al layered double hydroxide with nitrate anions nanosheets can be effectively realized by modulating reactant concentrations, leading to the formation of nanolayered structure in favor of increasing electrolyte accessible active sites within electrodes. The optimized Ni–Al layered double hydroxide with nitrate anions achieves a high specific capacitance of 1616 F g−1 at 1 A g−1 together with a capacitance retention of 82% at 10 A g−1 and good cycling stability.