Fluorination?Enhanced Surface Stability of Cation?Disordered Rocksalt Cathodes for Li?Ion Batteries

Cation-disordered rocksalt (DRX) materials have emerged as a class of novel high-capacity cathodes for Li-ion batteries. However, the commercialization DRX will require reducing their capacity decay, which has been associated with oxygen loss during cycling. Recent studies show that fluorination can effectively reduce and improve cycling stability; however, underlying atomic-scale mechanisms remain elusive. Herein, using combination electrochemical measurements, scanning transmission electron microscopy, energy spectroscopy, correlation between properties structural evolution in Mn-redox-based cathodes, Li1.2Ti0.4–xMn0.4+xO2.0-xFx (x = 0 0.2) is examined. It found strongly suppresses amorphization void formation initiated from particle surface, therefore greatly enhancing cyclability cathode. A rocksalt-to-spinel-like transformation bulk further revealed, surprisingly contributes to gradual increase The results provide important insight design high long cycle life.