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Updated: Jun 21, 2026
Characterization of Electrode Materials for Lithium Ion and Sodium Ion Batteries Using Synchrotron Radiation Techniques
Published on: November 11, 2013
Stabilizing lattice oxygen interface with dual-functional NiFe2O4 coating and Ni/Fe co-doping strategy towards
Ying Lei1, Haiyan Zhang1, Changsheng Yang1
1School of Materials and Energy, Guangdong University of Technology, Guangzhou 510006, China.
Abstract:
P2-Na0.67Mn0.8Fe0.1Ni0.1O2 (MNF811) has garnered considerable attention due to its low cost and high energy density, while the poor structural and air stability and lattice oxygen evolution lead to undesirable electrochemical performance. Here, a NiFe2O4 surface coating triggering a Ni/Fe co-doping strategy has been reported to suppress lattice oxygen evolution, eliminate poor air stability and mitigate the detrimental P2-OP4 phase transition. Furthermore, the NiFe2O4 coating layer with air stability protects P2-Na0.67Mn0.8Fe0.1Ni0.1O2 (MFN811@NF) cathode from reacting with moist air, and endows the P2-Na0.67Mn0.8Fe0.1Ni0.1O2 electrode with three-dimensional fast sodium-ion diffusion channels and stable cathode/electrolyte interface (CEI), benefiting from the NiFe2O4 coating layer. Ni/Fe co-doping by increasing the hybridization of the O(2p)- transition metal (TM) (3d-eg*) states, stabilizes excited state lattice oxygen and suppresses the irreversible migration of TM ions and the Jahn-Teller effect, mitigating adverse phase transitions and inhibiting structural degradation. In comparison to the Na0.67Mn0.8Fe0.1Ni0.1O2 electrode, the initial discharge capacity of the 10 % NiFe2O4-coated P2-Na0.67Mn0.8Fe0.1Ni0.1O2 (MFN811@NF-10) cathode was 114.4 mA h g-1 in the voltage range of 1.5-4.3 V at a high current density of 5C, with a capacity retention rate of 66.7 % after 1000 cycles. Eventually, the ex-situ X-ray Powder Diffraction (XRD) and ex-situ X-ray photoelectron spectroscopy (XPS) revealed that NiFe2O4 coating layer and Ni/Fe co-doping can prevent structural/chemical transformations and stabilize excited state lattice oxygen to realize high specific capacity. Density functional theory (DFT) calculations also confirm that Ni/Fe co-doping stabilizes lattice oxygen through the strengthening of transition metal-oxygen bonds. This dual modification strategy may provide crucial insights for the development of high-performance sodium-ion battery cathode materials.
