A porous puckered V2O5 polymorph as new high performance cathode material for aqueous rechargeable zinc batteries

Aqueous rechargeable zinc batteries are getting increasing attention for large-scale energy storage owing to their advantages in terms of cost, environmental friendliness and safety. Here, the layered puckered gamma'-V2O5 polymorph with a porous morphology is firstly introduced as cathode for an aqueous zinc battery system in a binary Zn2+/Li+ electrolyte. The Zn parallel to gamma'-V2O5 cell delivers high capacities of 240 and 190 mAh g(-1) at current densities of 29 and 147 mA g(-1), respectively, and remarkable cycling stability in the 1.6 V-0.7 V voltage window (97% retention after 100 cycles at 0.15 A g(-1)). The detailed structural evolution during first discharge-charge and subsequent cycling is investigated using X-ray diffraction and Raman spectroscopy. We demonstrate a reaction mechanism based on a selective Li insertion in the 1.6 V-1.0 V voltage range. It involves a reversible exchange of 0.8 Li+ in gamma'-V2O5 and the same structural response as the one reported in lithiated organic electrolyte. However, in the extended 1.6 V-0.7 V voltage range, this work puts forward a concomitant and gradual phase transformation from gamma'-V2O5 to zinc pyrovanadate Zn3V2O7(OH)(2 center dot)2H(2)O (ZVO) during cycling. Such mechanism involving the in-situ formation of ZVO, known as an efficient Zn and Li intercalation material, explains the high electrochemical performance here reported for the Zn parallel to gamma'-V2O5 cell. This work highlights the peculiar layered-puckered gamma'-V2O5 polymorph outperforms the conventional alpha-V2O5 with a huge improvement of capacity of 240 mAh g(-1) vs 80 mAh g(-1) in the same electrolyte and voltage window. (C) 2021 Science Press and Dalian Institute of Chemical Physics, Chinese Academy of Sciences. Published by ELSEVIER B.V. and Science Press. All rights reserved.

Automated summary

In this study, the porous layered puckered gamma'-V2O5 polymorph was introduced as a cathode for aqueous zinc batteries, exhibiting high capacity and cycling stability in a binary Zn2+/Li+ electrolyte. The work reveals a reaction mechanism based on selective Li insertion and gradual phase transformation to Zn pyrovanadate ZVO during cycling, explaining the high electrochemical performance of the system. This study highlights the superiority of gamma'-V2O5 over conventional alpha-V2O5 in terms of capacity and performance.