Conductive-free Zn2GeO4 @multi-walled carbon nanotubes for high-performance lithium-ion storage

A new composite of Zn2GeO4 @multi-walled carbon nanotubes (Zn2GeO4 @MWCNTs) has been synthesized by using a facial microwave assisted hydrothermal method, and found that the Zn2GeO4 nanorods were anchored on the surface of MWCNTs and embedded into the voids of MWCNTs aggregation, which could provide a conductive network for fast transport of ion and a buffer space for volumetric change during the charge-discharge process. The MWCNTs in the composite has also acted as conductive agent, avoiding the use of additional conductive agents. When used as an anode for LIBs, this composite delivered a high specific capacity of 1397.9 mA h g-1 at 0.2 A g-1 after 300 cycles, an excellent rate capability and long cycling stability over1800 cycles at a high rate of 1.0 A g-1. The results of in situ X-ray diffraction (XRD) measurements showed that the Li22Ge5 was formed during the discharge process, and others were amorphous phase, which can provide more active sites for lithium storage, and is beneficial to the fast diffusion of lithium ion, resulting in superb cycling performance.