Search

The development of aqueous rechargeable Zn metal batteries, as one of the most promising large‐scale energy storage technology, is hindered largely by dendrite growth and surface passivation of Zn metal anode, which are deleterious to the battery life and Coulombic efficiency (CE). This report demonstrates that ethylenediamine tetramethylenephosphonic acid can in situ coordinate with Zn (EDTMP‐Zn) along with exposing (002) planes for highly reversible and stable Zn plating/stripping. The zincophilic EDTMP‐Zn layer may serve as ion sieves that homogenize Zn ion flux at the Zn anode surface and consequently induce uniform deposition of Zn. The hydrophobic groups in such functional layer is thought to circumvent the Zn anode surface from corrosion and hydrogen evolution reaction. EDTMP15‐Zn modified Zn anode (EDTMP15‐Zn@Zn) delivers a lifespan exceeding 1400 h at 5 mA cm−2, and 1 mAh cm−2 for Zn||Zn symmetric cell and improved CE of 99.7% over 1000 cycles in a Zn||Cu cell. The full cell coupled with NH4V4O10 cathode demonstrates improved rate performance and cycle stability. [ABSTRACT FROM AUTHOR]

For the development of aqueous zinc‐ion batteries, exploiting vanadium‐based cathode materials with quick kinetics and acceptable cycling stability is crucial. Herein, to achieve these goals, transition metal ions (Zn2+) and organic ions (C5H14ON+ and Ch+) are introduced into layered hydrated V2O5. The intrinsic high conductivity of Ch+ and the oxygen vacancies generated through ion pre‐intercalation accelerate the electrical mobility by optimizing the electronic structure. The Zn2+ stabilizes the layered structure and the expanded interlayer spacing improves the ionic diffusivity. The synergistic effect of pre‐intercalated Zn2+ and Ch+ results in the (Zn0.1, Ch0.1)V2O4.92·0.56H2O cathode exhibiting a discharge capacity of 473 mAh g−1 at 0.1 A g−1 with a high energy efficiency of 88% and excellent cycling stability with 91% retention after 2000 cycles at 4 A g−1. Ex situ characterizations and density functional theory calculations reveal a reversible intercalation mechanism of Zn2+, and the improved electrochemical kinetics are attributed to the altered electronic conductivity and the reduced binding energy between Zn2+ and host O2−. [ABSTRACT FROM AUTHOR]

The electrochemical properties of vanadium-based materials as cathode materials for aqueous zinc ion batteries are still restricted by low conductivity, sluggish reaction kinetics, and poor structural stability. Herein, the [VO 6 ] octahedron, as the basic unit of vanadium-oxide layer of ammonium vanadates (NH 4 V 4 O 10 , denoted as NVO), is incorporated by F atoms to regulate the coordinated environment of vanadium. Density functional theory (DFT) calculations and experimental results show that both physicochemical and electrochemical properties of NVO are improved by F-doping. The enhanced electronic conductivity accelerates the electron transfer and the expanded interlayer spacing expedites the diffusion kinetics of zinc ions. As a result, the F-doped NVO (F-NVO) electrode shows a high discharge capacity (465 mAh g -1 at 0.1 A g -1 ), good rate capability (260 mAh g -1 at 5 A g -1 ), and long-term cycling stability (88% capacity retention over 2000 cycles at 4 A g -1 ). The reaction kinetics and energy storage mechanism of F-NVO are further validated by in situ and ex situ characterizations., (© 2023 Wiley‐VCH GmbH.)