Na0.67Mn(1‐x)FexO2 Compounds as High‐Capacity Cathode Materials for Rechargeable Sodium‐Ion Batteries. Issue 3 (14th December 2020)

• Record Type: Journal Article
• Authors: Siriwardena, Dumindu P.; Fernando, Joseph F. S.; Wang, Tony; Firestein, Konstantin L.; Zhang, Chao; Lewis, Courtney‐Elyce; von Treifeldt, Joel E.; Golberg, Dmitri V.
• Is Part Of: ChemElectroChem. Volume 8:Issue 3(2021)
• Page Start: 508
• Page End: 516
• Publication Date: 2020-12-14
• Subjects: Batteries -- Fe substitution -- high capacity -- P2-type -- sodium; Electrochemistry -- Periodicals; 541.37
• DOI: 10.1002/celc.202001297
• Languages: English
• ISSNs: 2196-0216

Abstract

Abstract: Herein, we report on electrochemical and structural properties of low‐cost Na0.67 Mn(1‐x) Fex O2 (NMFx ) cathode materials synthesized through substitution of Mn with small amounts of Fe. The materials were fabricated using a simple solid‐state synthesis method. Electrochemical performance of the cathodes was significantly improved when initial electrochemical activation had been performed. Activated Na0.67 Mn0.9 Fe0.1 O2 material displayed a high capacity of 132 mAh/g after 100 cycles and delivered an exceptionally high rate capability of 116 mAh/g at 500 mA/g. Energy‐dispersive X‐ray spectroscopy (EDX), cyclic voltammetry (CV) and ex situ X‐ray photoelectron‐spectroscopy (XPS) analyses suggested that Fe had played a structural as well as an electrochemical role in cathode performance. Ex situ and in situ X‐ray diffraction (XRD) studies were used to analyze the associated structural variations during the capacity evolution. Abstract : Deficient is not insufficient : Fe substitution into a Na‐deficient layered transition‐metal oxide is achieved. Structural and electrochemical analyses reveal that Fe stabilizes the structure and is electrochemically active. An electrochemical activation step substantially improves the cathode performance. In situ and ex situ XRD techniques are employed to explain the structural variations during electrochemical cycling of the best performing cathode in a 1.5–4.5 V potential range vs. Na/Na + .