不同碳源合成Na2MnPO4F/C及其作为锂离子电池正极材料的性能

采用湿法球磨和原位热解碳包覆相结合的方法, 分别以硬脂酸、柠檬酸、聚乙二醇-6000 (PEG-6000)、β-环糊精为碳源, 制备了不同结构的Na₂MnPO₄F/C 复合材料, 并研究了它们作为锂离子电池正极材料的电化学行为. 通过X射线衍射(XRD)、扫描电镜(SEM)、BET比表面积测试、恒流充放电等表征手段, 比较和分析了产物的结构、形貌及电化学性能. 研究结果表明, 由不同碳源制备的材料在形貌和颗粒尺寸上有明显差异, 进而对它们的电化学性能造成很大影响. 影响电化学性能的关键因素在于材料一次颗粒的大小. 其中, 以柠檬酸为碳源制备的样品呈现出典型的微纳结构和最小的一次颗粒(10-40 nm). 并给出最佳的电化学性能: 在1.5-4.8 V电压范围内, 以5 mA·g^-1充放电电流获得的首次放电比容量约为80 mAh·g^-1, 且循环稳定性良好.

Synthesis of Na2MnPO4F/C with Different Carbon Sources and Their Performances as Cathode for Lithium Ion Battery

Na₂MnPO₄F/C composites were synthesized by wet ball milling and in situ pyrolytic carbon coating. Stearic acid, citric acid, poly(ethylene glycol) 6000, and β-cyclodextrin were used as carbon sources in the synthesis process. The structures, morphologies, and electrochemical performances of the as-synthesized Na₂MnPO₄F/C composites were further investigated by X-ray diffraction (XRD), scanning electron microscopy (SEM), Brunauer-Emmett-Teller surface area analysis, and galvanostatic chargedischarge tests. Distinct differences were observed in the morphologies and sizes of the Na₂MnPO₄F/C particles obtained from different carbon sources, and this significantly affected their electrochemical performances. It was found that the primary particle size of the Na₂MnPO₄F/C material is a key factor in the electrochemical performance. The sample synthesized using citric acid as the carbon source had a micro-nano structure, with the smallest primary particle size of 10-40 nm, and displayed the best electrochemical properties. It delivered an initial discharge capacity of 80 mAh·g^-1 under a current density of 5 mA·g^-1 in the voltage range of 1.5-4.8 V, and displayed good cycling performance.