Structural Stabilization of P2‐type Sodium Iron Manganese Oxides by Electrochemically Inactive Mg Substitution: Insights of Redox Behavior and Voltage Decay. Issue 22 (5th October 2020)

• Record Type: Journal Article
• Authors: Yang, Junghoon; Maughan, Annalise E.; Teeter, Glenn; Tremolet de Villers, Bertrand J.; Bak, Seong‐Min; Han, Sang‐Don
• Is Part Of: ChemSusChem. Volume 13:Issue 22(2020)
• Page Start: 5972
• Page End: 5982
• Publication Date: 2020-10-05
• Subjects: layered sodium iron manganese oxides -- Mg substitution -- phase transition -- redox behavior -- voltage decay; Green chemistry -- Periodicals; Sustainable engineering -- Periodicals; Chemistry -- Periodicals; Chemical engineering -- Periodicals; 660
• DOI: 10.1002/cssc.202001963
• Languages: English
• ISSNs: 1864-5631

Abstract

Abstract: Layered P2‐type Na0.8 Mn0.5 Fe0.5 O2 cathode material is a promising candidate for next‐generation sodium‐ion batteries due to the economical and environmentally benign characteristics of Mn and Fe. The poor cycling stability of the material, however, is still a problem that must be solved. To address the problem, electrochemically inactive Mg 2+ was introduced into the structure by substituting some of the Fe ions. It was shown that Mg substitution led to a smoother voltage profile with improved cycling performance and rate capability. These observations were attributed to the suppressed structural changes during electrochemical processes. Detailed redox mechanisms, associated local structural changes, and phase transitions were investigated by X‐ray absorption spectroscopy and X‐ray diffraction. From the detailed analysis of electrochemical behaviors, it was also identified how the redox reactions and structural disordering occurred in the high‐ and low‐voltage regions and how Mg substitution stabilized the structure. Abstract : Not just a substitute : Introduction of electrochemically inactive Mg 2+ into P2‐type Na0.8 Mn0.5 Fe0.5 O2 cathode leads to improved cycling performance. Detailed redox mechanisms and associated local structural changes and phase transitions are provided to reveal the role of Mg 2+ substitution.