Elucidating the Intercalation Pseudocapacitance Mechanism of MoS₂–Carbon Monolayer Interoverlapped Superstructure: Toward High-Performance Sodium-Ion-Based Hybrid Supercapacitor

Two-dimensional (2D) layered materials have shown great promise for electrochemical energy storage applications. However, they are usually limited by the sluggish kinetics and poor cycling stability. Interface modification on 2D layered materials provides an effective way for increasing the active sites, improving the electronic conductivity, and enhancing the structure stability so that it can potentially solve the major issues on fabricating energy storage devices with high performance. Herein, we synthesize a novel MoS₂-carbon (MoS₂-C) monolayer interoverlapped superstructure via a facile interface-modification route. This interlayer overlapped structure is demonstrated to have a wide sodium-ion intercalation/deintercalation voltage range of 0.4-3.0 V and the typical pseudocapacitive characteristics in fast kinetics, high reversibility, and robust structural stability, thus displaying a large reversible capacity, a high rate capability, and an improved cyclability. A full cell of sodium-ion hybrid supercapacitor based on this MoS₂-C hybrid architecture can operate up to 3.8 V and deliver a high energy density of 111.4 Wh kg^-1 and a high power density exceeding 12 000 W kg^-1. Furthermore, a long cycle life of 10 000 cycles with over 77.3% of capacitance retention can be achieved.