Ultrathin Zn2(OH)3VO3 Nanosheets: First Synthesis, Excellent Lithium-Storage Properties, and Investigation of Electrochemical Mechanism.

Abstract

Nowadays, exploiting novel electrode materials is widely accepted as a key for meeting the growing demands of high-performance lithium ion batteries. Several transition-metal vanadates, which can in situ form an elastic buffer to adapt the volume expansion during lithium uptake/removal, have recently attracted much attention as anode materials, since they have high capacity and superior cycling stability. Herein, Zn2(OH)3VO3 nanostructures are successfully fabricated for the first time by a facile hydrothermal method and also first studied as lithium ion anode material. The ultrathin Zn2(OH)3VO3 nanosheets deliver a high reversible capacity close to 900 mAh g(-1) at a current density of 1 A g(-1) over 100 cycles. Even at a high current rate of 5 A g(-1), capacity retention as high as 83% (by compared with the second discharge capacity) is still obtained after 500 cycles, showing a high-rate capability. Moreover, we also carefully investigated the lithium-storage mechanism of Zn2(OH)3VO3, and corresponding results reveal that the Zn2(OH)3VO3 nanosheets have in situ transformed into ZnO nanoparticles anchoring on lithiated vanadium oxides matrix. The synergistic effect of zinc and vanadium oxides upon lithium ions intercalation and the stable conductive skeleton of amorphous lithiated vanadium oxides matrix both contribute to the excellent battery performance of Zn2(OH)3VO3 nanosheets. Finally, a full cell composed of lithiated Zn2(OH)3VO3/LiFePO4 with a high energy density of 293 Wh kg(-1) (vs total mass of active materials) at the current density of 100 mA g(-1) was successfully assembled, which could cycle well over 100 cycles with 79% capacity retention and also exhibit good rate stability. Thus, we believe that our research demonstrates a promising anode material for lithium ion batteries.