Reversible Ammonium Ion Intercalation/de-intercalation with Crystal Water Promotion Effect in Layered VOPO4⋅2 H2O**

作     者：Dr. Fei Ye Ruilvjing Pang Chengjie Lu Qiang Liu Prof. Yuping Wu Dr. Renzhi Ma Prof. Linfeng Hu 

作者机构：School of Materials Science and Engineering Southeast University Nanjing 211189 China Contribution: Conceptualization (equal) Data curation (equal) Formal analysis (lead) ​Investigation (lead) Writing - original draft (equal) Contribution: Data curation (lead) Formal analysis (lead) Validation (lead) Contribution: Software (lead) Writing - original draft (supporting) Contribution: Formal analysis (equal) ​Investigation (equal) Software (equal) School of Energy and Environment Southeast University Nanjing 211189 P. R. China Contribution: Funding acquisition (equal) Writing - review & editing (equal) Research Center for Materials Nanoarchitectonics (MANA) National Institute for Materials Science (NIMS) Namiki 1–1 Tsukuba Ibaraki 305-0044 Japan Contribution: Conceptualization (lead) Formal analysis (equal) Writing - review & editing (equal) Contribution: Conceptualization (lead) Funding acquisition (lead) Project administration (lead) Supervision (lead) Visualization (lead) Writing - original draft (lead) 

出 版 物：《Angewandte Chemie》 

年 卷 期：2023年第135卷第24期

学科分类：081704[工学-应用化学] 08[工学] 0817[工学-化学工程与技术] 

主　　题：Aqueous Ammonium-Ion Batteries Discharge Plateau Intercalation/De-Intercalation Layered Framework VOPO4⋅2 H2O 

摘      要：The non-metal NH 4 + carrier has attracted tremendous interests for aqueous energy storage owing to its light molar mass and fast diffusion in aqueous electrolytes. Previous study inferred that NH 4 + ion storage in layered VOPO 4 ⋅2 H 2 O is impossible due to the removal of NH 4 + from NH 4 VOPO 4 leads to a phase change inevitably. Herein, we update this cognition and demonstrated highly reversible intercalation/de-intercalation behavior of NH 4 + in layered VOPO 4 ⋅2 H 2 O host. Satisfactory specific capacity of 154.6 mAh g −1 at 0.1 A g −1 and very stable discharge potential plateau at 0.4 V based on reference electrode was achieved in VOPO 4 ⋅2 H 2 O. A rocking-chair ammonium-ion full cell with the VOPO 4 ⋅2 H 2 O//2.0 M NH 4 OTf//PTCDI configuration exhibited a specific capacity of 55 mAh g −1 , an average operating voltage of about 1.0 V and excellent long-term cycling stability over 500 cycles with a coulombic efficiency of ≈99 %. Theoretical DFT calculations suggest a unique crystal water substitution process by ammonium ion during the intercalation process. Our results provide new insight into the intercalation/de-intercalation of NH 4 + ions in layered hydrated phosphates through crystal water enhancement effect.