一种合成橄榄石结构 LiMn1−xCoxPO4/C 高压阴极的可扩展方法,Journal of Applied Electrochemistry

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一种合成橄榄石结构 LiMn1−xCoxPO4/C 高压阴极的可扩展方法
Journal of Applied Electrochemistry ( IF 2.384 ) Pub Date : 2021-01-14 , DOI: 10.1007/s10800-020-01528-8
Redouan El-Khalfaouy , Servet Turan , Miguel A. Rodriguez , Kamil Burak Dermenci , Umut Savacı , Abdellah Addaou , Ali Laajeb , Ahmed Lahsini

化学式为 LiMn1−xMxPO4（其中 M = Fe、Ni、Co...）的橄榄石基正极被认为是潜在的候选材料，具有高电压应用的可行性，提高了对各种电池组件和环境条件的稳定性。然而，扩大材料合成的技术仍然是一个挑战。溶液燃烧法在其他合成方法中处于领先地位，因为它可以合成大量具有更高均匀性和可重复性的材料。在这项研究中，使用甘氨酸作为燃料源，淀粉作为附加碳源，通过改进的溶液燃烧法 (SC) 合成了橄榄石基 LiMn1−xCoxPO4@C 正极材料。所有样品的 X 射线衍射表征表明高度结晶的斜方晶橄榄石结构。此外，它证实了 Co2+ 按比例替代了过渡金属 Mn2+ 而没有结构变化。电子显微镜和拉曼结果表明，纳米尺寸的颗粒具有有限的团聚和非常薄的碳涂层。电化学结果表明，共掺杂可以提高原始 LiMnPO4/C 材料的循环和高倍率性能。在所有掺杂样品中，LiMn0.99Co0.01PO4/C 表现出最好的倍率性能和循环稳定性，在 C/20 时最高的初始放电容量为 157 mAhg-1，库仑效率高达 98.1%，高于原始样品 LiMnPO4/C (80.38%)。作为潜在影响；这项工作揭示了通过 SC 方法开发具有最佳性能的高压阴极的结构-性能-过程关系。

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A scalable approach for synthesizing olivine structured LiMn1−xCoxPO4/C high-voltage cathodes

Olivine based cathodes with a chemical formula of LiMn1−xMxPO4 (where M = Fe, Ni, Co…) are considered as a potential candidate with their viability of high voltage applications, improved stability against various battery components and ambient conditions. However, the technology for scaling up the material synthesis remains a challenge. Solution combustion method stood forward among the other synthesis methods since it is possible to synthesize large quantities of materials with improved homogeneity and repeatability. In this study, olivine based LiMn1−xCoxPO4@C cathode materials were synthesized by a modified solution combustion method (SC) using glycine as fuel source, and starch as an additional carbon source. X-ray diffraction characterization of all samples suggested a highly crystallized orthorhombic olivine structure. In addition, it confirmed that Co2+ substitutes proportionately the transition metal Mn2+ without structural changes. Electron microscopy and Raman results pointed out the nanometer sized particles with a limited agglomeration and very thin carbon coating was successfully done. Electrochemical results suggested that Co-doping can improves cycling and high-rate capability of the pristine LiMnPO4/C material. Among all doped samples, LiMn0.99Co0.01PO4/C exhibited the best rate capability and cycling stability and the highest initial discharge capacity of 157 mAhg−1 at C/20, with a remarkable coulombic efficiency of about 98.1%, which is higher compared to that of the pristine sample LiMnPO4/C (80.38%). As a potential impact; this work reveals structure–property-process relationships for developing high-voltage cathodes by SC method targeted the best performance.

更新日期：2021-01-14

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