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The solid-state reaction between NaF and VPO 4 is widely used to produce Na 3 V 2 (PO 4 ) 2 F 3 , a promising cathode material for sodium-ion batteries. In the present work, the mechanism and kinetics of the reaction between NaF and VPO 4 were investigated, and the effect of preliminary high-energy ball milling (HEBM) was studied using in situ time-resolved synchrotron powder X-ray diffraction, in situ transmission electron microscopy, differential scanning calorimetry, etc. The reaction was attributed to a "dimensional reduction" formalism; it proceeds quickly with the unilateral diffusion of Na + and F − ions into VPO 4 particles as a limiting stage. The use of HEBM leads to the mechanism corresponding to the third-order reaction model and accelerates the interaction. The rate constant k increases from 3.5 × 10 −5 to 3.4 × 10 −3 s −1 , and diffusion coefficient D increases from 2 × 10 −14 to 4 × 10 −13 cm 2 s −1 when HEBM is used. The calculated apparent activation energy is ∼290 kJ mol −1 . The electrochemical properties of the asprepared Na 3 V 2 (PO 4 ) 2 F 3 are not inferior to the properties of the materials prepared by conventional solid-state synthesis.

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Lithium-excess oxides Li1.2Ti0.4Mn0.4O2 and Li1.3Nb0.3Mn0.4O2 with a disordered rock-salt structure and Mn3+/Mn4+ as a redox couple were compared to analyze the effect of different d0 metal ions on the local structure and Li+ ion migration.