Work-function-induced interfacial built-in electric field optimized electronic structure of V-CoSx@NiTe as high capacity and robust electrode for supercapacitors

The pursuit of achieving high energy density and exceptional stability in supercapacitors presents both allure and challenge. Herein, we strategically engineered hierarchical V-CoSx@NiTe core-shell heterojunction nanorod arrays, with V-doped amorphous CoSx nanosheets as the shell and one-dimensional (1D) NiTe nanorods as the core on nickel foam (NF). Theoretical computations elucidated the disparate intrinsic work functions of V-CoSx and NiTe, culminating in a robust built-in electric field at the interface. This field orchestrated interfacial charge distribution, expediting electron transport and optimizing OH– adsorption. V doping enhanced electronic states density at the Fermi energy level of CoSx and introduced new reaction sites. Additionally, the good hydrophilic properties and unique hierarchical core-shell morphology of the amorphous V-CoSx@NiTe/NF electrodes were favorable for increasing the specific surface area, improving the structural stability and facilitating the diffusion of OH–. Consequently, V-CoSx@NiTe/NF attained an impressive areal capacitance of 10.52 F cm−2 at 2 mA cm−2, preserving energy storage performance, morphology, and composition across 15,000 cycles. An asymmetric supercapacitor (ASC) device constructed with V-CoSx@NiTe/NF as the positive electrode and commercial activated carbon (AC) as the negative electrode exhibited energy (power) density of 0.42 mWh cm−2 (1.63 mW cm−2), and maintained ∼100 % capacity after 10,000 cycles. Significantly, a single device powered both a fan and a light bulb, while two devices in series illuminated a blue light-emitting diode (LED) for up to 2 h. This investigation introduces an innovative strategy for designing high-performance supercapacitor anode materials.