Regulating the local charge distribution in NiCo2O4@CoWO4 anode materials for hybrid asymmetric supercapacitors

Abstract

A desirable material with high surface area and optimized electronic properties is urgently required to boost the supercapacitors performance. Herein, we develop a hierarchical heterogeneous electrode material of NiCo₂O₄@CoWO₄/NF with nano-needles combined core-shell structure. This hierarchical heterogeneous electrode material features optimized interface charge distribution, which improves the electron transfer rate and storage density. In addition, we propose a mechanism concerning that the heterogeneous interface improves the surface electron delocalization to enhances the hydroxyl adsorption energy. The hydroxyl adsorption energy is increased from 0.95 eV to 1.13 eV in the presence of NiCo₂O₄@CoWO₄ heterogeneous interface. As a result, the reaction kinetics between the electroactive center of NiCo₂O₄ and the collector is enhanced under the strong interfacial coupling of CoWO₄, a specific capacity as high as 1624 C g⁻¹ (with a current density of 1 A g⁻¹), and an energy density of 88.38 Wh kg⁻¹ (with a power density of 884.78 W kg⁻¹) with a wide voltage window of 0-1.7 V. In addition, it also shows surprising cycling stability with 98% capacity retention after 10,000 cycles at a current density of 10 A g⁻¹. This work provides a new strategy for optimizing the surface and interfacial electronic properties of heterostructure materials.