Controllable preparation of 2D nickel aluminum layered double hydroxide nanoplates for high-performance supercapacitors

Optimizing the composition of nanostructured transition metal oxides and hydroxides has been proven to be an effective approach to alter the electrochemical performance of the materials. In this study, we synthesized and optimized the molar ratios of Ni/Al in NiAl LDH nanoplates by a facile hydrothermal method. Among the studied samples, the Ni_0.65Al_0.35 LDH electrode exhibited higher electrochemical performance than other studied compositions, resulting in a prominent specific capacitance of 1733.3 F g⁻¹ at 1 A g⁻¹ and high cycling stability of 87.1% after 5000 cycles at a current density of 5 A g⁻¹. An asymmetric supercapacitor device assembled with the optimized Ni_0.65Al_0.35 LDH as positive electrode and graphene as negative electrode delivered a high energy density of 32.6 Wh kg⁻¹ at a power density of 700 W kg⁻¹ along with excellent cycling performance of 93.2% after 5000 cycles at a current density of 5 A g⁻¹. The optimized Ni_0.65Al_0.35 LDH nanoplates hold great promise as advanced electrode materials for high-performance energy storage devices.