Wuhan University of Technology

About: Wuhan University of Technology is a education organization based out in Wuhan, China. It is known for research contribution in the topics: Microstructure & Catalysis. The organization has 40384 authors who have published 36724 publications receiving 575695 citations. The organization is also known as: WUT.

Identification of Phase Control of Carbon-Confined Nb2O5 Nanoparticles toward High-Performance Lithium Storage

Abstract: DOI: 10.1002/aenm.201802695 developing advanced electrochemical energy storage devices with high energy/ power density and long lifespan.[1] Among them, lithium-ion batteries (LIBs) and supercapacitors (SCs) are two most promising devices for chemical energy storage.[2] However, there has been an obvious research boundary between them owing to their different charge-storage mechanisms. Generally, LIBs provide high energy density but relatively low power density on basis of insertion-, conversion-, and alloying-type mechanisms, while SCs exhibit high power density and relatively good cycling stability but low energy density via a fast physisorption and/or shallow redox reaction on the electrode/electrolyte interface.[3] Therefore, to meet the market need and conquer the energy storage barrier, developing advanced LIBs with supercapacitor-like rate performance that combines both merits is a very challenging research direction with vital importance in the near future.[4] There is no doubt that the intrinsic phase structures of electrode materials play a crucial role in improving battery performance.[5] Compared with conversion-/ alloying-type materials, most insertion-type materials have robust crystalline skeletons and relatively high diffusion efficiency during charging and discharging, which can endow LIBs with long-term cycling stability and high rate capability.[6] Niobium pentoxides (Nb2O5) have attracted extensive interest for ultrafast lithium-ion batteries due to their impressive rate/capacity performance and high safety as intercalation anodes. However, the intrinsic insulating properties and unrevealed mechanisms of complex phases limit their further applications. Here, a facile and efficient method is developed to construct three typical carbon-confined Nb2O5 (TT-Nb2O5@C, T-Nb2O5@C, and H-Nb2O5@C) nanoparticles via a mismatched coordination reaction during the solvothermal process and subsequent controlled heat treatment, and different phase effects are investigated on their lithium storage properties on the basis of both experimental and computational approaches. The thin carbon coating and nanoscale size can endow Nb2O5 with a high surface area, high conductivity, and short diffusion length. As a proof-ofconcept application, when employed as LIB anode materials, the resulting T-Nb2O5@C nanoparticles display higher rate capability and better cycling stability as compared with TT-Nb2O5@C and H-Nb2O5@C nanoparticles. Furthermore, a synergistic effect is investigated and demonstrated between fast diffusion pathways and stable hosts in T-Nb2O5 for ultrafast and stable lithium storage, based on crystal structure analysis, in situ X-ray diffraction analysis, and density functional theoretical calculations. Therefore, the proposed synthetic strategy and obtained deep insights will stimulate the development of Nb2O5 for ultrafast and long-life LIBs.