Carbon materials together with various redox electrolytes have been developed intensively in recent years to assemble large-capacitance and high-rate supercapacitors. However, the weak interactions between carbon electrodes and redox electrolytes result in the severe shuttle of redox ions in electrolytes, causing critical self-discharge performance. Here we report a functional interface to establish strong adhesion of redox ions on the liquid side towards carbon nanotube arrays, leading to efficient confinement of redox ions around carbon electrode and enhanced electronic transfer between the electrode and redox electrolyte. Benefiting from the interface, the coupling carbon nanotube arrays-K₃Fe(CN)₆ system exhibits a substantially boosted self-discharge rate with no decay after 32 h under the open-circuit stage, as well as a large areal capacitance up to 3.048 F cm⁻². The introduction of functionalized interface suggests a general and versatile concept for carbon-based electrodes to achieve battery-like charge storage with reliable features.