Boosting Zn-Ion Storage Performance of Bronze-Type VO₂ via Ni-Mediated Electronic Structure Engineering

Abstract

Aqueous rechargeable zinc-ion batteries are emerging as attractive alternatives for postlithium-ion batteries. However, their electrochemical performances are restricted by the narrow working window of materials in aqueous electrolytes. Herein, Ni-mediated VO 2 -B nanobelt ((Ni)VO 2 ) has been designed to optimize the intrinsic electronic structure of VO 2 -B, and thus achieve much more enhanced zinc-ion storage. Specifically, the Zn/(Ni)VO 2 battery yields good rate capability (182.0 mAh g -1 at 5 A g -1 ) with superior cycling stability (130.6 mAh g -1 at 10 A g -1 after 2000 cycles). Experimental and theoretical methods reveal that the introduction of Ni 2+ in the VO 2 tunnel structure can effectively provide high surface reactivity and improve the intrinsic electronic configurations, thus resulting in good kinetics. Furthermore, H + and Zn 2+ co-intercalation processes are determined via in-situ X-ray diffraction and supported by ex-situ characterizations. Additionally, quasi-solid-state Zn/(Ni)VO 2 soft-packaged batteries are assembled and provide flexibility in battery design for practical applications. The results provide insight into the interrelationships between the intrinsic electronic structure of the cathode and overall electrochemical performance.

A Reversible Anodizing Strategy in a Hybrid Electrolyte Zn-Ion Battery through Structural Modification of a Vanadium Sulfide Cathode

“…The ex situ Raman study during the charging/discharging process shows the appearance of six peaks at 319.15, 352.07, 581.91, 766.21, 866.09, and 1035.21 cm –1 . The peaks at 766.21 and 1035.21 cm –1 are attributed to the stretching vibration of V–O and V–O–V modes, respectively. , The additional peaks at 300–500 and 866.09 cm –1 are ascribed to the formation of Zn 3 (OH) 2 V 2 O 7 ·2H 2 O and Zn x (OTf) y (OH) 2 x − y · n H 2 O phases as reported in the literature. ,, Furthermore, the electrochemical performance of the Zn//MVS2 device was measured in the 0.1 M H 2 SO 4 ACN/water hybrid electrolyte as shown in Figure S15. The device exhibits 53.52 mA h g –1 specific capacity at 0.2 A g –1 current density.…”

“… ,, Another crystalline phase is located at 2θ ≈ 23.85° for the orthorhombic sulfur. The orthorhombic sulfur peak repeatedly appears and disappears during the discharging/charging process of the electrode, indicating an additional capacity contribution due to the reversible in situ anodization of sulfur. ,,,− Therefore, a partial conversion of VS 4 to Zn 3 (OH) 2 V 2 O 7 ·2H 2 O and orthorhombic sulfur is observed during the discharging process with water and Zn 2+ ion reactants. Furthermore, the poor crystallinity of the Zn x (OTf) y (OH) 2 x − y · n H 2 O phase is indexed to the 2θ ≈ 34.87 and 48.35° plane, and the peaks frequently appear/disappear with potential cycling.…”

“…3 (OH) 2 V 2 O 7 •2H 2 O and Zn x (OTf) y (OH) 2x−y •nH 2 O phases as reported in the literature 46,49,51. Furthermore, the electrochemical performance of the Zn//MVS2 device was measured in the 0.1 M H 2 SO 4 ACN/water hybrid electrolyte as shown in FigureS15.…”

“…Furthermore, the poor crystallinity of the Zn x (OTf) y (OH) 2x−y •nH 2 O phase is indexed to the 2θ ≈ 34.87 and 48.35°plane, and the peaks frequently appear/ disappear with potential cycling. This reversible phenomenon indicates that the H + and Zn 2+ ion insertion/extraction process occurs simultaneously 16,21,46,49. During the initial discharging, a large number of protons are inserted into the cathode, and the hydroxyl groups in the electrolyte increase, resulting in the formation of the Zn x (OTf) y (OH) 2x−y •nH 2 O crystal phase.…”

Long-Life Zinc/Vanadium Pentoxide Battery Enabled by a Concentrated Aqueous ZnSO4 Electrolyte with Proton and Zinc Ion Co-Intercalation

“…Recently, manganese oxides, − Prussian blue analogues, , spinel oxides, , organic materials, , and vanadium-based compounds − have been studied as potential positive electrodes for RZBs. Among them, vanadium oxides hold great prospects because of their affordability, multi-electron redox reactions, and large ion transfer channels. − …”