Interfacial engineering in amorphous/crystalline heterogeneous nanostructures as a highly effective battery-type electrode for hybrid supercapacitors

Abstract

Hybrid supercapacitors (HSCs) as a novel electronic device for electrical energy storage have attractive prospects due to their high specific power and fast charge/discharge rates. However, the low gravimetric energy density, sluggish frequency reply, and relatively low voltage range of HSCs limit their practical applications. Meanwhile, efficient energy storage faces challenges such as building effective electrode microstructures. Here, interfacial and structural engineering by developing a disordered structure, creating a synergy interface, and introducing an amorphous and crystalline synergistic system is employed to tailor their electrochemical properties. The resulting 1D crystalline NiCo₂O₄ anchored on carbon cloth (CC/NiCo₂O₄) can improve the kinetics of chemical reactions, and the amorphous “short-range order” and sheet-like two-dimensional structure of NiCo-(HPO₄)₂·H₂O (NiCo–P) are beneficial to expose more active sites, and easily alleviate the volume change of the kinetic process. Thus, the obtained CC/NiCo₂O₄@NiCo–P exhibits a high specific capacity of 1254.2 C g⁻¹ at 1 A g⁻¹, a remarkable specific energy of 54.83 W h kg⁻¹ and an outstanding cycling stability of 80.2%. By density functional theory (DFT) calculations, it is found that the superior electrical conductivity and strong adsorption to OH– of the CC/NiCo₂O₄@NiCo–P hybrid structure provide powerful theoretical help for improving electrochemical performance. This work provides new insights into the design of HSCs with enhanced properties and enables applications of crystalline-amorphous materials for energy storage and conversion devices.