Synthesis and Electrochemical Performance of KVO/GO Composites as Anodes for Aqueous Rechargeable Lithium-Ion Batteries.

K 0.25 V 2 O 5 (KVO) and K 0.25 V 2 O 5 /graphene oxide (KVO/GO) have been successfully synthesized by a chemical coprecipitation method and a subsequent calcination process. The structure and morphology of KVO and KVO/GO were characterized by X-ray diffraction, scanning electron microscopy, transmission electron microscopy, and X-ray photoelectron spectroscopy. The as-obtained vanadate and vanadate modified by GO materials were used as anodes with LiMn 2 O 4 as a cathode and saturated LiNO 3 as an electrolyte to assemble an aqueous rechargeable lithium-ion battery (ARLB). The cyclic voltammogram curves of both KVO and KVO/GO electrodes exhibited three pairs of redox peaks corresponding to charge/discharge platforms. We found that a small amount of graphene oxide added improved the electrochemical performance more significantly than excess graphene oxide. The as-prepared KVO/GO//LiMn 2 O 4 could not only improve the initial discharge capacity but could also reduce the attenuation at a high current density. Furthermore, the ARLB with a KVO/GO anode exhibited an excellent rate performance and super long cycle life. These good electrochemical properties of this new ARLB system actually provided feasibility for application in large-scale power sources and energy storage devices.