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

VO (B) features two lithiation/delithiation processes, one of which is kinetically facile and has been commonly observed at 2.5 V versus Li/Li in various VO (B) structures. In contrast, the other process, which occurs at 2.1 V versus Li/Li , has only been observed at elevated temperatures due to large interaction energy barrier and extremely sluggish kinetics. Here, it is demonstrated that a rational design of atomically thin, 2D nanostructures of VO (B) greatly lowers the interaction energy and Li -diffusion barrier. Consequently, the kinetically sluggish step is successfully enabled to proceed at room temperature for the first time ever. The atomically thin 2D VO (B) exhibits fast charge storage kinetics and enables fully reversible uptake and removal of Li ions from VO (B) lattice without a phase change, resulting in exceptionally high performance. This work presents an effective strategy to speed up intrinsically sluggish processes in non-van der Waals layered materials.