Microstructure evolution of Li uptake/removal in MoO₂@C nanoparticles with high lithium storage performance

By Liu, Yulong; Zhang, Hong; Ouyang, Pan; Chen, Wenhao & Li, Zhicheng
Published in Materials Research Bulletin NULL 2014

Abstract

A facile one pot strategy of a hydrothermal methodology was applied to synthesize the carbon coated MoO₂ (MoO₂@C) nanostructured particles, which are composed of ultra fine nanoparticles with homogeneous carbon coating about several nanometers. As an electrode in lithium ion batteries, the MoO₂@C shows a high specific capacity and reversible capacity (730 mA h g-1 after 60 cycles). Microstructure investigations, by using a high resolution transmission electron microscopy, of the MoO₂@C based electrodes employed at various states during the first discharge/charge cycle were conducted to elucidate the lithium ion uptake/removal mechanism and cycling behavior. In the lithium uptake process, the original MoO₂ phase transfers into Li₀.₉₈MoO₂ through an addition type reaction, and then nanosized metallic Mo emerges as a result of a conversion reaction. In turn, Mo could be oxidized to the intermediate Li₀.₉₈MoO₂ before converting to hyperfine MoO₂ phase on upcoming lithium removal process.

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