Measuring T1 relaxation in paramagnetic solids with solid-state NMR: a case study on the milling induced phase transition in Li6CoO4

作者：Guo, Nianrui; Geng, Fushan; Lu, Guozhong; Jiang, Xinbiao; Li, Chao; Hu, Bingwen; Shen, Ming^*

来源：Physical Chemistry Chemical Physics, 2023, 25(17): 12065-12071.

DOI：10.1039/d3cp00757j

• ANIONIC REDOX ACTIVITY
• IRON-OXIDE
• LITHIUM
• CATHODE
• SPECTROSCOPY
• DYNAMICS
• ORIGIN
• METAL

Solid-state NMR has been a vital tool for the study of structural evolution of cathodes in lithium-ion and sodium-ion batteries. However, the differentiation of relaxation parameters for certain sites is difficult owing to limited spectral resolution associated with strong anisotropic hyperfine interaction. Here we propose a novel IR-pjMATPASS method that can measure T-1 relaxation with site-specific resolution for paramagnetic solids. We apply this method to the characterization of ball-milling induced order-disorder phase transition in Li6CoO4 as a case study. The quasi-quantitate Li-7 NMR enables the synthetic optimization of high energy ball-milling conditions to harvest a disordered cubic phase through site-specific Li-7 T-1 measurements. The example study shown here provides a quantitative strategy for NMR studies of paramagnetic solids.