NH<sub>4</sub><sup>+</sup> Deprotonation at Interfaces Induced Reversible H<sub>3</sub>O<sup>+</sup>/NH<sub>4</sub><sup>+</sup> Co‐insertion/Extraction
Meng Huang, Qiu He, Junjun Wang, Xiong Liu, Fangyu Xiong, Yu Liu, Ruiting Guo, Yan Zhao, Jinlong Yang, Liqiang Mai
Abstract
Abstract Ion insertions always involve electrode‐electrolyte interface process, desolvation for instance, which determines the electrochemical kinetics. However, it′s still a challenge to achieve fast ion insertion and investigate ion transformation at interface. Herein, the interface deprotonation of NH 4 + and the introduced dissociation of H 2 O molecules to provide sufficient H 3 O + to insert into materials′ structure for fast energy storages are revealed. Lewis acidic ion‐NH 4 + can, on one hand provide H 3 O + itself via deprotonation, and on the other hand hydrolyze with H 2 O molecules to produce H 3 O + . In situ attenuated total reflection‐Fourier transform infrared ray method probed the interface accumulation and deprotonation of NH 4 + , and density functional theory calculations manifested that NH 4 + tend to thermodynamically adsorb on the surface of monoclinic VO 2 , and deprotonate to provide H 3 O + . In addition, the inserted NH 4 + has a positive effect for stabilizing the VO 2 (B) structure. Therefore, high specific capacity (>300 mAh g −1 ) and fast ionic insertion/extraction (<20 s) can be realized in VO 2 (B) anode. This interface derivation proposes a new path for designing proton ion insertion/extraction in mild electrolyte.