Abstract Rechargeable aqueous batteries with Zn2+as a working‐ion are promising candidates for grid‐scale energy storage because of their intrinsic safety, low‐cost, and high energy‐intensity. However, suitable cathode materials with excellent Zn2+‐storage cyclability must be found in order for Zinc‐ion batteries (ZIBs) to find practical applications. Herein, NaCa0.6V6O16·3H2O (NaCaVO) barnesite nanobelts are reported as an ultra‐stable ZIB cathode material. The original capacity reaches 347 mAh g−1at 0.1 A g−1, and the capacity retention rate is 94% after 2000 cycles at 2 A g−1and 83% after 10 000 cycles at 5 A g−1, respectively. Through a combined theoretical and experimental approach, it is discovered that the unique V3O8layered structure in NaCaVO is energetically favorable for Zn2+diffusion and the structural water situated between V3O8layers promotes a fast charge‐transfer and bulk migration of Zn2+by enlarging gallery spacing and providing more Zn‐ion storage sites. It is also found that Na+and Ca2+alternately suited in V3O8layers are the essential stabilizers for the layered structure, which play a crucial role in retaining long‐term cycling stability. 
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                            Structural impact of Zn-insertion into monoclinic V 2 (PO 4 ) 3 : implications for Zn-ion batteries
                        
                    
    
            The zinc-ion battery (ZIB) has been a system of particular interest in the research community as a possible alternative to lithium-ion batteries (LIB), and much work has been devoted to finding a suitable host material. In this article, monoclinic V 2 (PO 4 ) 3 is investigated as a host material for reversible insertion of Zn 2+ . Initial chemical assessment via a facile microwave-assisted chemical insertion method indicates the possibility of Zn 2+ insertion into the host. Electrochemical assessment, however, exhibits a significant capacity fade. In-depth analysis on the average and local structure of Li 3 V 2 (PO 4 ) 3 , the empty host V 2 (PO 4 ) 3 , and the Zn-inserted V 2 (PO 4 ) 3 reveals that heavy distortion is induced upon Zn 2+ insertion into the V 2 (PO 4 ) 3 framework, which is believed to be a result of a strong host–guest interaction jeopardizing the structural integrity. This is further supported by the dissolution of most of the material during the chemical oxidation of the Zn-inserted V 2 (PO 4 ) 3 . The underlying structural inadequacy poses difficulties for monoclinic V 2 (PO 4 ) 3 to be a viable reversible host for Zn-ion batteries. This work suggests that not only the electrostatic repulsions of multivalent ions in a structure during diffusion, but also the structural stability of the host upon insertion of multivalent ions, must be considered for a better design of suitable host materials for multivalent-ion batteries. 
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                            - Award ID(s):
- 1709081
- PAR ID:
- 10095601
- Date Published:
- Journal Name:
- Journal of Materials Chemistry A
- Volume:
- 7
- Issue:
- 12
- ISSN:
- 2050-7488
- Page Range / eLocation ID:
- 7159 to 7167
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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