Defects enriched cobalt molybdate induced by carbon dots for a high rate Li-ion battery anode

A defects-enriched CoMoO₄/carbon dot (CD) with CoMoO₄around 37 nm is achieved via hydrothermal reaction by introducing CDs to buffer large volume changes of CoMoO₄during lithiation-delithiation and enhance rate performance. The phase, morphology, microstructure, as well as the interface of the CoMoO₄/CD composites were investigated by x-ray diffraction, scanning electron microscopy, transmission electron microscopy and x-ray photoelectron spectroscopy. When employed as Li-ion battery anode, the CoMoO₄/CD exhibits a reversible capacity of ∼531 mAh g^-1after 400 cycles at a current density of 2.0 A g^-1. Under the scan rate at 2 mV s^-1, the CoMoO₄/CD shows accounts for 81.1% pseudocapacitance. It may attribute to the CoMoO₄with surface defects given more reaction sites to facilitate electrons and lithium ions transfer at high current densities. Through galvanostatic intermittent titration technique, the average lithium ion diffusion coefficient calculated is an order of magnitude larger than that of bulk CoMoO₄, indicating that the CoMoO₄/CD possesses promising electrons and lithium ions transportation performance as anode material.