Fast, completely reversible Li insertion in vanadium pentoxide nanoribbons

Layered-structure nanoribbons with efficient electron transport and short lithium ion insertion lengths are promising candidates for Li battery applications. Here we studied at the single nanostructure level the chemical, structural, and electrical transformations of V₂O₅ nanoribbons. We found that transformation of V₂O₅ into the ω-Li₃V₂O₅ phase depends not only on the width but also the thickness of the nanoribbons. Transformation can take place within 10 s in thin nanoribbons, suggesting a Li diffusion constant 3 orders of magnitude faster than in bulk materials, resulting in a significant increase in battery power density (360 C power rate). For the first time, complete delithiation of ω-Li₃V₂O₅ back to the single-crystalline, pristine V₂O₅ nanoribbon was observed, indicating a 30% higher energy density. These new observations are attributed to the ability of facile strain relaxation and phase transformation at the nanoscale. In addition, efficient electronic transport can be maintained to charge a Li₃V₂O₅ nanoribbon within less than 5 s. These exciting nanosize effects can be exploited to fabricate high-performance Li batteries for applications in electric and hybrid electric vehicles.