Unravelling the Fast Alkali‐Ion Dynamics in Paramagnetic Battery Materials Combined with NMR and Deep‐Potential Molecular Dynamics Simulation

• Published in: Angewandte Chemie 2021-05, Vol.133 (22), p.12655-12661
• Main Authors: Lin, Min, Liu, Xiangsi, Xiang, Yuxuan, Wang, Feng, Liu, Yunpei, Fu, Riqiang, Cheng, Jun, Yang, Yong
• Format: Article
• Language: English
• Subjects: chemical exchange; Chemistry; deep potential; density functional calculations; Ion dynamics; Molecular dynamics; NMR; NMR spectroscopy; Nuclear magnetic resonance; paramagnetic solids; Room temperature; Simulation; Transition metals
• ISSN: 0044-8249; 1521-3757
• DOI: 10.1002/ange.202102740

Solid‐state nuclear magnetic resonance (ssNMR) has received extensive attention in characterizing alkali‐ion battery materials because it is highly sensitive for probing the local environment and dynamic information of atoms/ions. However, precise spectral assignment cannot be carried out by conventional DFT for high‐rate battery materials at room temperature. Herein, combining DFT calculation of paramagnetic shift and deep potential molecular dynamics (DPMD) simulation to achieve the converged Na+ distribution at hundreds of nanoseconds, we obtain the statistically averaged paramagnetic shift, which is in excellent agreement with ssNMR measurements. Two 23Na shifts induced by different stacking sequences of transition metal layers are revealed in the fast chemically exchanged NMR spectra of P2‐type Na2/3(Mg1/3Mn2/3)O2 for the first time. This DPMD simulation auxiliary protocol can be beneficial to a wide range of ssNMR analysis in fast chemically exchanged material systems. The unambiguous assignment of chemical shift in paramagnetic battery materials relies on first‐principles calculation, while the state‐of‐art computational methodology is limited in sluggish dynamic systems. We incorporate hundreds of nanoseconds deep potential molecular dynamics (DPMD) simulation to expanding the ssNMR application in high‐rate cathode materials.