Binder-free ZnO@ZnSnO₃ quantum dots core-shell nanorod array anodes for lithium-ion batteries

In this work, ZnSnO₃ quantum dots (QDs), instead of commonly used conductive carbon, are grown on the ZnO nanorod (NR) array to construct the binder-free ZnO@ZnSnO₃ QDs core-shell NR array electrode on carbon cloth for lithium-ion battery. The ZnO@ZnSnO₃ QDs core-shell NR array electrode exhibits excellent lithium storage performance with an improved cycling performance and superior rate capability compared to the ZnO NR array electrode. At a current density of 200 mAg⁻¹, 15.8% capacity loss is acquired in the ZnO@ZnSnO₃ QDs core-shell NR array electrode after 110 cycles with capacity retention of 1073 mAhg⁻¹. Significant increases in reversible capacities from 340 to 545 mAhg⁻¹ and from 95 to 390 mAhg⁻¹ at current densities of 1000 and 2000 mAg⁻¹, respectively, are achieved as the ZnO NR arrays are coated with the ZnSnO₃ QD shells. The remarkably improved electrochemical performances result from that the configuration of binder-free ZnO@ZnSnO₃ QDs core-shell NR array electrode not only facilitates the charge transfer through the solid electrolyte interface and the electronic/ionic conduction boundary as well as lithium ion diffusion but also effectively accommodates the volume change during repeated charge/discharge processes.