The development of an integrated energy devices and technologies has brought new demands for novel materials with multifunctional properties such as energy harvesting and storage. We report herein a core-shell-like hierarchical structure comprising a metal (three-dimensional (3D) Ni) core and a metalene (antimonene nanodendrite) shell that can store electrochemical energy and harvest energy via triboelectrification. Antimonene/3DNi nanostructures were fabricated via a facile, cost-effective electrochemical deposition technique. X-ray photoelectron spectroscopy and Raman mapping analysis revealed the growth of antimonene nanostructures less than 20 nm thick on the 3D Ni foam. Electrochemical studies established a high specific capacity of 1618.41 mA h g–1 (6854.45 F g–1) for the antimonene/3DNi electrode, which is superior over the reported Ni-foam based binder-free electrodes. The antimonene/3DNi electrode was used as a positrode in the fabrication of an asymmetric supercapacitor (ASC) with graphene based negatrode that provide a high energy density (84.79 Wh kg–1) and power density (20625 W kg–1). Kelvin probe force microscopy studies established that the antimonene/3DNi behaved as a positive-type tribo layer. It was then used in Sb-triboelectric nanogenerator device with Kapton as the negative tribo-layer to harvest a maximum output of ~54 V and ~0.87 μA with a peak power of 15 μW. The exceptional energy storage and harvesting properties of the antimonene/3DNi nanostructures were confirmed in a self-charging power system using a commercial capacitor and an ASC. This proof-of-concept will stimulate further research into using metalenes in next-generation energy devices.