储能科学与技术 ›› 2024, Vol. 13 ›› Issue (8): 2489-2498.doi: 10.19799/j.cnki.2095-4239.2024.0215

• 储能材料与器件 • 上一篇    下一篇

高倍率和长循环稳定性钠离子电池正极材料Na0.85Ni0.3Fe0.2Mn0.5O1.95F0.05 @CuO的性能研究

郝定邦(), 栗永利()   

  1. 华北电力大学能源动力与机械工程学院,北京 102206
  • 收稿日期:2024-03-12 修回日期:2024-03-30 出版日期:2024-08-28 发布日期:2024-08-15
  • 通讯作者: 栗永利 E-mail:db18500791096@163.com;yongli.li@ncepu.edu.cn
  • 作者简介:郝定邦(1999—),男,硕士研究生,研究方向为钠离子电池层状氧化物,E-mail:db18500791096@163.com
  • 基金资助:
    国家科技基础资源调查专项(2022FY101302)

Na0.85Ni0.3Fe0.2Mn0.5O1.95F0.05@CuO cathode materials for high-rate and long cycling stability sodium-ion batteries

Dingbang HAO(), Yongli LI()   

  1. School of Energy Power and Mechanical Engineering, North China Electric Power University, Beijing 102206, China
  • Received:2024-03-12 Revised:2024-03-30 Online:2024-08-28 Published:2024-08-15
  • Contact: Yongli LI E-mail:db18500791096@163.com;yongli.li@ncepu.edu.cn

摘要:

传统钠离子电池铁锰基正极材料具有价格低廉、理论比容量和工作电压高的优势,受到了广泛和深入的研究,但是铁锰基层状氧化物在充放电时晶体结构会发生不可逆相变,容量和循环稳定性会迅速衰退,不利于大规模应用和发展。针对这种问题,本工作采用阴离子F-掺杂和金属氧化物CuO包覆制备出P2/O3混合相Na0.85Ni0.3Fe0.2Mn0.5O1.95F0.05@CuO铁锰基正极材料,并分析了不同包覆温度下材料的电化学性能。扫描电子显微镜(SEM)、透射电子显微镜(TEM)和能量分散谱(EDS)显示CuO对材料表面实现了致密均匀包覆,非原位X射线衍射分析(ex-situ XRD)结果表明材料在充放电过程中未出现不可逆相变,晶体结构保持良好。Na0.85Ni0.3Fe0.2Mn0.5O1.95F0.05@CuO-800材料在2.0~4.2 V时首次放电容量为122.7 mAh/g,100圈循环后容量保持率为72.62%;在5C和10C大倍率充放电电流密度下经过200圈和800圈循环后放电比容量仍达到75 mAh/g和60 mAh/g,容量保持率为82%以上。结果表明F-掺杂形成的强TM—F键以及均匀致密包覆的CuO层保持了材料晶体结构的稳定性,抑制了不可逆O2相的产生,减少了电极材料与电解质之间副反应的发生,避免了因过渡金属离子的溶解造成正极材料剥落。本工作显著提升了材料在高倍率下的长循环性能,为高倍率和长循环稳定性的铁锰基正极材料设计提供了依据。

关键词: 钠离子电池, 复合相结构, 阴离子掺杂, 包覆改性, 结构转变

Abstract:

Traditional iron/manganese-based cathode materials for sodium-ion batteries have attracted extensive and in-depth research because of their low cost, high theoretical capacity, and high operating voltage advantages. However, iron-manganese-based layered oxides undergo irreversible phase transitions in their crystal structures during charging and discharging processes, leading to rapid capacity decay and reduced cycling stability, which hamper their large-scale application and development. To address this issue, this study employed anion F- doping and a metal oxide CuO coating to prepare a P2/O3 hybrid-phase Na0.85Ni0.3Fe0.2Mn0.5O1.95F0.05@CuO iron/manganese-based cathode material and investigated the electrochemical performance of the material at different coating temperatures. Scanning electron microscopy (SEM), transmission electron microscopy (TEM), and energy-dispersive spectroscopy (EDS) revealed a uniform coating of CuO on the material surface. An ex-situ X-ray diffraction (ex-situ XRD) analysis showed no irreversible phase transitions during charging and discharging processes, maintaining a well-preserved crystal structure. Na0.85Ni0.3Fe0.2Mn0.5O1.95F0.05 @CuO-800 exhibited an initial discharge capacity of 122.7 mAh/g at 2.0—4.2 V, with a capacity retention rate of 72.62% after 100 cycles. At high charging and discharging rates, current densities of 5 and 10 C, respectively, the discharge specific capacities remained at 75 and 60 mAh/g after 200 and 800 cycles, respectively, with a capacity retention rate of approxiamtely 82%. The strong TM—F bonds formed by F-doping combined with the uniform dense CuO coating layer maintained the stability of the crystal structure, suppressed the irreversible O2 phase generation, reduced the occurrence of side reactions between electrode materials and the electrolyte, and prevented the peeling of the cathode material caused by the dissolution of transition metal ions. This study significantly improved the long-term cycling performance of the iron/manganese-based cathode material under high rates; thus, it provided a basis for the design of iron/manganese-based cathode materials with high rate capability and long cycling stability.

Key words: sodium-ion batteries, hybrid-phase structure, anion doping, coating modification, phase transition

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