应用化学沉淀法合成了3种普鲁士蓝类化合物NaxMyFe(CN)6(M=Fe, Co, Ni),并研究以此类化合物作钠离子电池正极材料的可行性. XRD和SEM分析表明,合成的3种目标产物均具有典型的立方晶型结构,粒子尺寸约为20 ~ 50 nm. 循环伏安扫描和恒电流充放电测试表明,这类化合物均能实现可逆的钠离子嵌入-脱嵌反应,但不同的金属表现出不同的电化学性质. 如材料中的Fe(CN)64+和Fe2+/Co2+离子这两个电化学活性中心都能参与氧化还原反应,因此,NaFeFe(CN)6和Na2CoFe(CN)6的首周可逆容量分别为113 mAh?g-1和120 mAh?g-1,且循环性比较稳定. 由于这类结构中Ni离子不能参入氧化还原反应,导致Na2NiFe(CN)6的可逆容量仅为64 mAh?g-1,但循环性能非常优异. 本工作的初步结果证明了普鲁士蓝类化合物具有良好的钠离子脱嵌能力,有望成为一类价格低廉、环境友好的钠离子电池正极材料.
钱江锋
,
周敏
,
曹余良
,
杨汉西
. NaxMyFe(CN)6(M=Fe,Co,Ni):一类新颖的钠离子电池正极材料[J]. 电化学, 2012
, 18(2)
: 108
-112
.
DOI: 10.61558/2993-074X.2888
Three types of Prussian blue compounds, NaxMyFe(CN)6(M = Fe, Co, Ni), were prepared simply by solution precipitation method and tested as cathode materials for sodium-ion batteries. X-ray diffraction and SEM measurements demonstrated that the prepared materials, namely, NaFeFe(CN)6, Na2CoFe(CN)6, and Na2NiFe(CN)6, exhibited a perfect cubic structure with a particle size of several tens nanometers. Cyclic voltammetric and galvanostatic cycling tests revealed very different electrochemical behaviors of these three materials. The specific capacities of NaFeFe(CN)6 and Na2CoFe(CN)6 could reach 113 mAh?g-1 and 120 mAh?g-1, respectively, indicating that both of the Fe(CN)6-4 and Fe+2/Co+2 ions in the Prussian blue lattices were electrochemically activated. However, Ni ions in the Prussian blue lattice were found to be electrochemically inactive, therefore, the Na2NiFe(CN)6 delivered a specific capacity of only 64 mAh?g-1 but with quite stable cyclability. These preliminary results suggest a possible use of the Prussian blue compounds as low cost and environmentally benign cathode materials for sodium-ion batteries.
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