Construction of CoMoO4@NiMn-LDH Core-Shell Heterostructure on Nickel Foam for High-Performance Asymmetric Supercapacitors

To support smart grid technologies and mitigate the intermittency of renewable energy sources, efficient electrochemical energy storage is essential. Despite their inherent advantages, supercapacitors are constrained by insufficient energy density, limiting their practical deployment. To address this challenge, we report a hierarchical CoMoO 4 @NiMn-LDH core-shell heterostructure grown directly on nickel foam (NF) via a two-step hydrothermal method. The integration of a highly active NiMn-LDH nanosheet shell onto the CoMoO 4 nanorod core synergistically enhances electron transport and ion diffusion. Morphological characterization confirms the formation of a well-integrated porous structure comprising vertically oriented NiMn-LDH nanosheets encapsulating uniformly distributed CoMoO 4 nanorods. The synergistic interplay of structure and composition yields a CoMoO 4 @NiMn-LDH/NF electrode with a high areal capacitance of 17,869.6 mF cm −2 at 2 mA cm −2 , surpassing that of the corresponding single-component electrodes. Moreover, the electrode retains 79.74% of its capacitance at 10 mA cm −2 , demonstrating exceptional rate capability, and maintains 99.98% of its initial capacitance after 8000 charge–discharge cycles, indicating excellent structural stability. Kinetic analysis reveals a hybrid charge storage mechanism in which the capacitive contribution progressively increases at higher scan rates, facilitating rapid charge–discharge processes. An asymmetric supercapacitor assembled with this composite as the positive electrode and activated carbon as the negative electrode delivers an areal capacitance of 2593.25 mF cm −2 and a maximum energy density of 0.922 mWh cm −2 at a power density of 1.6 mW cm −2 . Overall, this study presents a versatile core–shell heterostructure design strategy for developing high-energy, high-power supercapacitor electrodes.