Large Intercalation Pseudocapacitance in 2D VO₂ (B): Breaking through the Kinetic Barrier

Area of Science:

• Materials Science
• Electrochemistry
• Nanotechnology

Background:

• Vanadium dioxide (VO2) in its B phase exhibits two lithiation/delithiation processes.
• A facile process occurs at 2.5 V vs. Li/Li+, while a sluggish process at 2.1 V vs. Li/Li+ requires elevated temperatures due to high energy barriers.

Purpose of the Study:

• To investigate if rational design of atomically thin, 2D nanostructures can overcome kinetic limitations in VO2 (B).
• To enable the sluggish lithiation/delithiation process to occur at room temperature.

Main Methods:

• Fabrication of atomically thin, 2D nanostructures of VO2 (B).
• Characterization of ion diffusion barriers and interaction energies in the nanostructures.
• Electrochemical testing at room temperature.

Main Results:

• Atomically thin, 2D VO2 (B) nanostructures significantly reduce interaction energy and Li+ diffusion barriers.
• The kinetically sluggish process at 2.1 V vs. Li/Li+ is successfully activated at room temperature for the first time.
• The material demonstrates fast charge storage kinetics and fully reversible Li+ uptake/removal without phase change.

Conclusions:

• Rational design of 2D nanostructures is an effective strategy to accelerate intrinsically sluggish processes in non-van der Waals layered materials.
• This approach leads to exceptionally high performance in VO2 (B) for energy storage applications.