CoNi2S4/NiCo-LDH/Cu2S multilevel heterostructure for high-performance supercapacitors

Layered double hydroxides (LDHs) are promising cathode materials for supercapacitors but are limited by insufficient active sites and poor reaction kinetics. To address this, this work develops a CoNi 2 S 4 /NiCo-LDH/Cu 2 S composite with a multilevel heterostructure via localized in-situ sulfidation. The structure features 1D Cu 2 S nanorods as a framework, 2D NiCo-LDH nanosheets providing high surface area, and 0D CoNi 2 S 4 nanoparticles grown in situ as additional active sites. This design enhances conductivity, surface area, and redox-active sites, promoting ion adsorption and migration. The electrode achieves an areal capacitance of 12.4 F cm −2 at 3 mA cm −2 and retains 80.6% at 20 mA cm −2 . The assembled asymmetric supercapacitor delivers an energy density of 1.29 mWh cm −2 and power density of 2.39 mW cm −2 , with 90.7% capacitance retention and 99.6% coulombic efficiency after 10,000 cycles. It also powers an LED and fan, demonstrating practical potential. This study offers new insights into designing high-performance electrodes through multilevel heterostructures and localized in-situ sulfidation.