储能科学与技术 ›› 2020, Vol. 9 ›› Issue (1): 57-64.doi: 10.12028/j.issn.2095-4239.2019.0142

• 储能材料与器件 • 上一篇    下一篇

络合剂对铁基普鲁士蓝结构及储钠性能的影响

龙宣有1(), 王捷1,2, 赵丽娜1, 赵海雷1,2(), 王康康3, 高飞3   

  1. 1. 北京科技大学材料科学与工程学院，北京 100083
    2. 新能源材料与技术北京市重点实验室，北京 100083
    3. 中国电力科学研究院有限公司新能源与储能运行控制国家重点实验室，北京 100192
  • 收稿日期:2019-06-25 修回日期:2019-07-10 出版日期:2020-01-05 发布日期:2019-08-05
  • 通讯作者: 赵海雷 E-mail:longxuanyou@126.com;hlzhao@ustb.edu.cn
  • 作者简介:龙宣有（1994—），女，硕士研究生，研究方向为钠离子电池电极材料，E-mail：longxuanyou@126.com；
  • 基金资助:
    国家自然科学基金(U1637202);北京市自然科学基金资助项目(2194079);国家电网有限公司科技项目(DG71-16-027)

Effect of chelating agent on crystal structure and sodium storage performance of Fe-based Prussian blue

LONG Xuanyou1(), WANG Jie1,2, ZHAO Lina1, ZHAO Hailei1,2(), WANG Kangkang3, GAO Fei3   

  1. 1. School of Materials Science and Engineering, University of Science and Technology Beijing, Beijing 100083, China
    2. Beijing Municipal Key Laboratory of New Energy Materials and Technologies, Beijing 100083, China
    3. State Key Laboratory of Operation and Control of Renewable Energy and Storage Systems, China Electric Power Research Institute, Beijing 100192, China
  • Received:2019-06-25 Revised:2019-07-10 Online:2020-01-05 Published:2019-08-05
  • Contact: Hailei ZHAO E-mail:longxuanyou@126.com;hlzhao@ustb.edu.cn

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摘要：

以普鲁士蓝及其衍生物为代表的新型储能材料，具有开放的框架结构，有利于钠离子的存储及快速迁移，作为钠离子电池正极材料具有很好的应用前景。其中，铁基普鲁士蓝材料由于资源丰富、制备过程简单、比容量高等优点，备受关注。普鲁士蓝的晶体结构对其电化学性能影响较大，特别是晶体中的钠含量、空位数量和结晶水含量。通过调整合成工艺参数，可以控制普鲁士蓝的晶体结构形式和组成。采用简单的共沉淀法，在制备过程中添加络合剂柠檬酸三钠，合成了富钠型铁基普鲁士蓝钠离子电池正极材料。借助X射线衍射技术（XRD）、扫描电子显微技术（SEM）、热重分析（TG）和电化学表征技术等测试方法分析了柠檬酸三钠络合剂在晶体结构形成中的作用，以及对材料电化学性能的影响。结果表明，添加络合剂制备出的铁基普鲁士蓝材料为单斜相，颗粒呈立方体状，结晶性和分散性良好，尺寸约400 nm。未添加络合剂的材料表现为立方相，颗粒为圆形，尺寸约150 nm，颗粒相互粘连出现明显团聚。单斜相样品具有钠含量高、水含量少的特征。用作钠离子电池正极材料，单斜相电极材料表现出更高的可逆比容量及更优异的循环性能和倍率性能。在30 mA/g的电流密度下，电极首次放电比容量为129.9 mA·h/g，库仑效率高达99.5%，循环100次后，容量保持率为75.7%。800 mA/g电流密度下的可逆比容量可达到45.3 mA·h/g。循环伏安测试和交流阻抗测试结果显示，单斜相电极材料相比于立方相电极材料具有更快的电化学反应动力学过程。文章还讨论了柠檬酸三钠络合剂在普鲁士蓝颗粒成核和生长过程中的作用机理。

关键词: 钠离子电池, 正极材料, 铁基普鲁士蓝, 络合剂

Abstract:

New energy storage materials comprising Prussian blue and its analogues exhibit promising application potential as positive electrode materials for sodium-ion batteries because of their open frame structure, which is beneficial for the storage and rapid migration of sodium ions. Among these, Fe-based Prussian blue has attracted considerable attention due to its abundant resources, simple preparation, and high specific capacity. The electrochemical performance of Prussian blue is strongly correlated with its lattice structure, especially the sodium content, vacancy concentration, and crystal water. The lattice structure of Prussian blue can be tuned by controlling the processing parameters. Herein, two types of Na-enriched Fe-based Prussian blue cathode materials were synthesized via a facile coprecipitation method with and without a chelating agent, i.e., sodium citrate. The effects of sodium citrate on the crystal structure formation and sodium storage performances were investigated using X-ray diffraction （XRD）, scanning electron microscopy, thermogravimetric analysis （TGA）, and electrochemical characterization techniques. The results denoted that the Fe-based Prussian blue material prepared using the chelating agent exhibited a monoclinic structure. The material exhibited a well-defined cubic particle morphology with an average size of approximately 400 nm and good crystallinity as well as particle dispersibility. However, the Prussian blue sample prepared without the chelating agent displayed a cubic lattice structure. The particles exhibited a spherical morphology with a size of approximately 150 nm and presented significant particle agglomeration. XRD and TGA revealed that the sample with a monoclinic structure had a high sodium content but a low water content per formula unit when compared to the cubic structure. As a sodium-ion battery cathode, the sample with the monoclinic structure exhibited a high reversible capacity of 129.9 mA·h/g, a high first-cycle coulombic efficiency of 99.5%, and a remarkable cycling performance with a capacity retention of 75.7% after 100 cycles at a current density of 30 mA/g. This electrode exhibited a good rate performance, and the reversible specific capacities were 129.3, 121.7, 116.7, 110.7, 87.8, 63.6, and 45.3 mA·h/g at a current density of 30, 50, 100, 200, 400, 600, and 800 mA/g, respectively. When the current density returned to 30 mA/g, the reversible specific capacity was restored to 117.3 mA·h/g. The cyclic voltammetry and electrochemical impedance tests indicated that the monoclinic Prussian blue electrode exhibited lower electrode polarization and charge transfer resistance when compared with that exhibited by the cubic sample, resulting in faster electrode reaction kinetics and an excellent electrochemical performance. The role of the chelating agent, i.e., sodium citrate, in the Prussian blue particle nucleation and growth processes is also discussed.

Key words: sodium ion battery, cathode material, Fe-based Prussian blue, chelating agent

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