Aqueous rechargeable lithium batteries using NaV6O15 nanoflakes as high performance anodes

Abstract

Poor cycling performance is still the big challenge for aqueous rechargeable lithium batteries (ARLBs), in which the instability of the anode is considered to be the main issue. In this work, NaV₆O₁₅ nanoflakes were synthesized by a two-step approach and a NaV₆O₁₅//LiMn₂O₄ ARLB system with superior cycling performance was constructed. The galvanostatic charge–discharge result demonstrates an initial discharge capacity of 110.7 mA h g⁻¹ (based on anode mass) at 150 mA g⁻¹ and the capacity retention of ca. 90% and 80% at 300 mA g⁻¹ after 100 and 400 cycles, respectively. Such superior cycling performance of ARLBs is mainly due to the intrinsic 3-D tunneled structure of NaV₆O₁₅, nanoflake morphology and relatively stable electrode surface, as verified by the X-ray diffraction (XRD), electrochemical impedance spectroscopy (EIS), and scanning electron microscopy (SEM) results of the tested electrodes. Moreover, a simple single-phase reaction mechanism during the lithium ion insertion/extraction process is observed for NaV₆O₁₅ by XRD analysis.