Synthesis of hierarchical NiCo-LDH and biphasic Co9S8/Co3S4 core–shell heterostructure for hybrid supercapacitor
摘要
Strategic interface engineering provides a powerful route to enhance both charge-transfer kinetics and electrolyte accessibility in electrochemical energy storage. Here, we introduce a scalable two-step hydrothermal synthesis of hierarchical NiCo‐LDH@Co9S8/Co3S4 core–shell heterostructures directly grown on three-dimensional nickel foam, followed by an oil bath treatment. Biphasic Co9S8/Co3S4 microcubes provide a highly conductive scaffold and rapid surface redox activity, while an epitaxial shell of ultrathin Ni–Co layered‐double‐hydroxide nanosheets delivers abundant pseudocapacitive sites and bulk ion intercalation. By systematically varying the Ni:Co ratio, we identify an optimal Ni:Co = 1:2 composition (NC‐LDH@CoS‐3) that maximizes active‐site density and structural stability. Detailed morphological (SEM/TEM), structural (XRD), surface-chemical (XPS), and porosity (BET) analyses confirm the presence of a three-dimensional mesoporous network with abundant heterointerfaces and built-in electric fields. Electrochemical evaluation reveals an ultrahigh specific capacitance of 2007 F g−1 at 1 A g−1, 76.4% capacitance retention at 10 A g−1, and robust cycling stability (90% retention after 5000 cycles in a three-electrode cell; 80% after 10,000 cycles in a full hybrid supercapacitor). The assembled device achieves an energy density of 94.9 Wh kg−1 at 720 W kg−1 and retains 55.6 Wh kg−1 at 11.8 kW kg−1. These results highlight the efficacy of heterojunction-enabled charge modulation within a porous nanoarchitecture, offering a cost-effective strategy for next-generation high-performance supercapacitor electrodes.