3D hierarchical nanoarrays composed of NiCo–Te multilayer nanoneedles modified with Co1.29Ni1.71O4 for high-performance hybrid supercapacitors

Abstract

Transition metal tellurides have been developed as electrodes for supercapacitors owing to their high pseudocapacitance and excellent electrical conductivity. However, the limited surface-active sites limit the improvement of capacity performance. Herein, the 3D hierarchical nanoarrays consisting of NiCo–Te nanoneedles modified with Co_1.29Ni_1.71O₄ were designed and synthesized on nickel foam (NF@NiCo–Te/Co_1.29Ni_1.71O₄). In particular, due to the design of bimetallic telluride structure with multiple oxidation states and the surface modification of bimetallic oxides with adequate active sites, the prepared NF@NiCo–Te/Co_1.29Ni_1.71O₄ shows rapid and invertible redox reaction during the process of energy storage. At the current density of 1.0 A g⁻¹, the as-prepared electrode material can express a high specific capacitance of 186.5 mA h g⁻¹ (1332 F g⁻¹). Significantly, electrolyte ions can easily complete intercalation and deintercalation due to the multilayer structure of nanoneedles, and the hybrid supercapacitors assembled by activated carbon (negative electrode) and NF@NiCo–Te/Co_1.29Ni_1.71O₄ (positive electrode) deliver a maximum energy density of 63.4 W h kg⁻¹ at 800 W kg⁻¹. In addition, the capacity retention ratio of NF@NiCo–Te/Co_1.29Ni_1.71O₄//AC remains 83.85% after 5000 high-current charge–discharge cycles. Therefore, the 3D architecture electrodes based on bimetallic tellurides with unique structures possess a great application value in energy storage.