Mechanism of Zn3v3o8@Zno@Nc Heterostructure for Stable Zinc  Storage from Assembling Nanodisks into Cross-Stacked Architecture

Abstract

In this work, the heterostructure of Zn 3 V 3 O 8 and ZnO coated by carbon with a Stenocactus-like morphology (Zn 3 V 3 O 8 @ZnO@NC) is proposed to serve as a cathode for AZIBs. And benefiting from the structural stability of the special morphology and electroconductibility of carbon, the electrode delivers remarkable long cyclic stability (120.5 mAh g -1 at 5 A g -1 after 2000 cycles). It also reveals a hyper-stable rate performance. The discharge capacity only reduces the 33.3 mAh g -1 with the current density increases (216.3 mAh g -1 and 183 mA h g -1 at 0.5 A g -1 and 3 A g -1 , respectively). Besides, the zinc ion storage mechanism of Zn 3 V 3 O 8 @ZnO@NC is revealed via ex-situ XRD and XPS. The results reveal that Zn 3 V 3 O 8 @ZnO@NC was transformed into Zn 3 (OH) 2 V 2 O 7 ·2H 2 O(ZOVO) during the first charge process when the voltage is between ca 1.2-14 V and the transformation is completed after the two cycles. After the second cycle, the energy storage is provided only by the de(intercalation) of Zn 2+ in ZOVO.

Keywords: Zn3V3O8@ZnO@NC heterostructure, Cross-stacked architecture, Nanodisks, Zn2+ storage, 3D interpenetrating network