Semykina Daria O, Sharafutdinov Marat R, Kosova Nina V
Institute of Solid State Chemistry and Mechanochemistry SB RAS, 18 Kutateladze, 630128 Novosibirsk, Russia.
Synchrotron Radiation Facility SKIF, Boreskov Institute of Catalysis SB RAS, 1 Nikol'skiy Prospekt, 630559 Kol'tsovo, Russia.
Inorg Chem. 2022 Jul 4;61(26):10023-10035. doi: 10.1021/acs.inorgchem.2c00951. Epub 2022 Jun 24.
The solid-state reaction between NaF and VPO is widely used to produce NaV(PO)F, a promising cathode material for sodium-ion batteries. In the present work, the mechanism and kinetics of the reaction between NaF and VPO were investigated, and the effect of preliminary high-energy ball milling (HEBM) was studied using time-resolved synchrotron powder X-ray diffraction, 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 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 increases from 3.5 × 10 to 3.4 × 10 s, and diffusion coefficient increases from 2 × 10 to 4 × 10 cm s when HEBM is used. The calculated apparent activation energy is ∼290 kJ mol. The electrochemical properties of the as-prepared NaV(PO)F are not inferior to the properties of the materials prepared by conventional solid-state synthesis.
NaF与VPO之间的固态反应被广泛用于制备NaV(PO)F，它是一种很有前景的钠离子电池正极材料。在本工作中，研究了NaF与VPO反应的机理和动力学，并使用时间分辨同步辐射粉末X射线衍射、透射电子显微镜、差示扫描量热法等研究了预高能球磨（HEBM）的影响。该反应归因于“降维”形式；它以Na和F离子单向扩散到VPO颗粒中作为限制阶段快速进行。使用HEBM导致反应机理符合三级反应模型并加速了相互作用。当使用HEBM时，速率常数从3.5×10增加到3.4×10 s，扩散系数从2×10增加到4×10 cm s。计算得到的表观活化能约为290 kJ mol。所制备的NaV(PO)F的电化学性能不低于通过传统固态合成制备的材料的性能。
