Self-assembled 3D network GeOx/CNTs nanocomposite as anode material for Li-ion battery

Abstract

Ge-based materials are promising alternative anode materials for Li-ion batteries (LIBs) because of their high theoretic specific capacity, as well as high intrinsic electronic conductivity and Li-ion diffusivity compared with Si-based materials. However, their industrial application has been limited by their inherent problem of volume expansion (~260%) upon Li+ insertion/extraction. Here, we report a GeOx/CNT nanocomposite with a self-assembled three-dimensional (3D) network structure that can be applied as an anode material in LIBs. The nanocomposite is synthesised through an in situ reduction route wherein GeOx particles are selectively grown on the surface of CNTs. The material is studied through X-ray diffraction, X-ray photoelectron spectrometry, Raman spectroscopy, scanning electron microscopy, transmission electron microscopy and electrochemical techniques. When used as an anode material for LIBs, the cycling performance and rate capability of the synthesised GeOx/CNTs nanocomposite are superior to those of pure GeOx particles. The GeOx/CNT composite can deliver a discharge capacity of 753.8 mAh g−1 after 100 charge/discharge cycles at 160 mA g−1 even under the high current density of 3.2 A g−1 and achieves a reversible capacity of 554.8 mAh g−1. The excellent Li storage performance of the material is attributed to its unique self-assembled 3D network structure, which provides a stable conductive network and effectively buffers the drastic volume changes experienced by GeOx particles during charge–discharge cycling.