Rod-like anhydrous V2O5 assembled by tiny nanosheets as a high-performance cathode material for aqueous zinc-ion batteries.

Weijun Zhou,Xinwu Xu,Junling Xu,Minfeng Chen,Jizhang Chen,Qinghua Tian,Ching-Ping Wong

doi:10.1039/c9ra06143f

Abstract

Aqueous zinc-ion batteries offer a low-cost and high-safety alternative for next-generation electrochemical energy storage, whereas suitable cathode materials remain to be explored. Herein, rod-like anhydrous V2O5 derived from a vanadium-based metal–organic framework is investigated. Interestingly, this material is assembled by tiny nanosheets with a large surface area of 218 m2 g−1 and high pore volume of 0.96 cm3 g−1. Benefiting from morphological and structural merits, this material exhibits excellent performances, such as high reversible capacity (449.8 mA h g−1 at 0.1 A g−1), good rate capability (314.3 mA h g−1 at 2 A g−1), and great long-term cyclability (86.8% capacity retention after 2000 cycles at 2 A g−1), which are significantly superior to the control sample. Such great performances are found to derive from high Zn2+ ion diffusion coefficient, large contribution of intercalation pseudocapacitance, and fast electrochemical kinetics. The ex situ measurements unveil that the intercalation of Zn2+ ion is accompanied by the reversible V5+ reduction and H2O incorporation. This work discloses a direction for designing and fabricating high-performance cathode materials for zinc-ion batteries and other advanced energy storage systems.

Highlights

IntroductionMn-based oxides (e.g., MnO2,8–12 Mn3O4,13 and ZnMn2O4 (ref. 14)), polyanionic compounds (e.g., Na3V2(PO4)2F3 (ref. 15) and LiV2(PO4)[3] (ref. 16)), Prussian blue analogues,[17] Mo-based compounds (e.g., MoS2 (ref. 18)), and organic and polymer compounds (e.g., polyaniline[19,20,21] and pchloranil22) have been investigated as the cathode materials for aqueous zinc-ion batteries (AZIBs)
Zinc element is abundant on the earth, and its metallic form is stable in water and has an approximate redox potential of À0.76 V vs. standard hydrogen electrode (SHE), allowing metallic Zn to be directly used as the anode of aqueous zinc-ion batteries (AZIBs) with a large theoretical speci c capacity (820 mA h gÀ1 and 5855 mA h cmÀ3).[4,7]
In order to demonstrate the importance of morphology engineering for V2O5 cathode material and elucidate its Zn2+ ion uptake mechanism, we focus on rod-like anhydrous V2O5 that is fabricated via the pyrolysis of MIL-47

Summary

Introduction

Mn-based oxides (e.g., MnO2,8–12 Mn3O4,13 and ZnMn2O4 (ref. 14)), polyanionic compounds (e.g., Na3V2(PO4)2F3 (ref. 15) and LiV2(PO4)[3] (ref. 16)), Prussian blue analogues,[17] Mo-based compounds (e.g., MoS2 (ref. 18)), and organic and polymer compounds (e.g., polyaniline[19,20,21] and pchloranil22) have been investigated as the cathode materials for AZIBs. 18)), and organic and polymer compounds (e.g., polyaniline[19,20,21] and pchloranil22) have been investigated as the cathode materials for AZIBs. In recent years, Mn-based oxides 18)), and organic and polymer compounds (e.g., polyaniline[19,20,21] and pchloranil22) have been investigated as the cathode materials for AZIBs These materials suffer from either low speci c capacity or poor rate capability or short life span. It is found that RA-V2O5 possesses micro/nano-hierarchical structure with large speci c surface area and high pore volume, displaying great electrochemical performances

Materials synthesis and characterization

Electrochemical measurements

Results and discussion

Conclusions