School of Materials Science and Engineering, Southeast University, Nanjing, 211189, China.
School of Energy and Environment, Southeast University, Nanjing, 211189, P. R. China.
Angew Chem Int Ed Engl. 2023 Jun 12;62(24):e202303480. doi: 10.1002/anie.202303480. Epub 2023 May 4.
The non-metal NH 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 ion storage in layered VOPO ⋅2 H O is impossible due to the removal of NH from NH VOPO leads to a phase change inevitably. Herein, we update this cognition and demonstrated highly reversible intercalation/de-intercalation behavior of NH in layered VOPO ⋅2 H O host. Satisfactory specific capacity of 154.6 mAh g at 0.1 A g and very stable discharge potential plateau at 0.4 V based on reference electrode was achieved in VOPO ⋅2 H O. A rocking-chair ammonium-ion full cell with the VOPO ⋅2 H O//2.0 M NH OTf//PTCDI configuration exhibited a specific capacity of 55 mAh g , 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 ions in layered hydrated phosphates through crystal water enhancement effect.
由于其轻摩尔质量和在水性电解质中的快速扩散，非金属 NH 载体在水系储能中引起了极大的兴趣。先前的研究推断，由于从 NH VOPO 中去除 NH 会不可避免地导致相转变，因此 NH 离子在层状 VOPO ⋅2 ⋅H O 中的存储是不可能的。在此，我们更新了这一认知，并证明了 NH 在层状 VOPO ⋅2 ⋅H O 主体中具有高度可逆的插层/脱插层行为。在 VOPO ⋅2 ⋅H O 中实现了基于参考电极的 0.1 A ⋅g 时 154.6 mAh ⁇ g 的出色比容量和非常稳定的 0.4 V 放电电位平台。具有 VOPO ⋅2 ⋅H O//2.0 M NH OTf//PTCDI 构型的摇椅式铵离子全电池表现出 55 mAh ⁇ g 的比容量、约 1.0 V 的平均工作电压和出色的长期循环稳定性，超过 500 次循环，库仑效率约为 99 ⁇ %。理论 DFT 计算表明，在插层过程中，铵离子通过独特的晶水取代过程。我们的结果通过晶水增强效应提供了对 NH 离子在层状水合磷酸盐中的插层/脱插层的新见解。
