喷雾干燥法制备Na_(2)MnPO_(4)F/C正极材料及其电化学性能研究

Spray-drying Synthesis of Na_(2)MnPO_(4)F/C Cathode Materials and its Electrochemical Properties

本文采用喷雾干燥法制备了Na_(2)MnPO_(4)F/C复合正极材料,研究了合成温度对样品的结构、形貌及电化学性能的影响。研究表明,600~750℃下均能合成出单一的Na_(2)MnPO_(4)F,各样品均无杂相,随着温度的升高样品的结晶度增大。SEM结果表明,在较低温度(600~650℃)下合成的样品颗粒细小且分布均匀,而较高温度(700~750℃)下合成的样品颗粒明显增大且团聚较为严重。电化学测试结果表明,650℃下合成的Na_(2)MnPO_(4)F/C具有最优的电化学性能,该样品在0.05和0.1 C下的首次放电比容量为52.1和25.5 mAh/g,且具有较好的倍率和循环性能。

Na_(2)MnPO_(4)F/C composite cathode materials are synthesized by a spray-drying method in this paper,and the effect of calcination temperature on the structure,morphology and electrochemical performance of the samples are studied in detail.The study results show that a single Na_(2)MnPO_(4)F phase can be successfully synthesized at the calcination temperatures of 600~750℃,and no impurity phase is detected.The crystallinity of the sample increases with the increase of temperature.SEM results show that the samples synthesized at lower temperatures(600~650℃)exhibit fine particles and evenly distributed,while the samples synthesized at higher temperature(700~750℃)exhibit lager particles and agglomerated seriously.Electrochemical test shows that the Na_(2)MnPO_(4)F/C sample synthesized at 650℃has the optimal electrochemical properties.The sample shows an initial discharge specific capacities of 52.1 mAh/g at 0.05C rate,and exhibits good rate capability and cycling performance.