Energy Storage Science and Technology ›› 2024, Vol. 13 ›› Issue (8): 2489-2498.doi: 10.19799/j.cnki.2095-4239.2024.0215

• Energy Storage Materials and Devices • Previous Articles     Next Articles

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

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

CLC Number: