Effect of nickel and iron on structural and electrochemical properties of O3 type layer cathode materials for sodium-ion batteries

• Published in: Journal of power sources 2016-08, Vol.324, p.106-112
• Main Authors: Hwang, Jang-Yeon, Myung, Seung-Taek, Aurbach, Doron, Sun, Yang-Kook
• Format: Article
• Language: English
• Subjects: Cathode material; Crystal structure; Electrochemical analysis; Electrodes; High temperature; Iron; Layered structure; Nickel; O3-type; Oxalate; Rechargeable batteries; Sodium ion battery; Thermal properties
• ISSN: 0378-7753; 1873-2755
• DOI: 10.1016/j.jpowsour.2016.05.064

We investigate that the effect of Ni and Fe contents on structural and electrochemical properties of O3-type layered Na[Ni0.75−xFexMn0.25]O2 (x = 0.4, 0.45, 0.5, and 0.55) in which Mn is fixed at 25%. As increasing the Ni contents, the capacities are gradually higher while the capacity retention and thermal properties are inferior. When Fe contents are increased, by contrast, the electrode exhibits stable capacity retention and satisfactory thermal stability although the resulting capacity slightly decreases. Structural investigation of post cycled electrodes indicate that lattice variation is greatly suppressed from x = 0.5 in Na[Ni0.75−xFexMn0.25]O2. This indicates that an appropriate amount of Fe into the Na[Ni0.75−xFexMn0.25]O2 stabilizes the crystal structure and this leads to the good cycling performances. Also, the better structural stability obtained by Fe addition is responsible for the less heat generation at elevated temperature for the desodiated Na1−δ[Ni0.75−xFexMn0.25]O2 (x = 0.4, 0.45, 0.5, and 0.55) caused by less evaporation of oxygen from the crystal structure. •We investigate the effect of Ni and Fe contents on O3-type NFM cathode.•The Ni contents contribute to a higher discharge capacity.•An appropriate amount of Fe contents improves the electrochemical properties.•The resulting demonstrates an appropriate balancing of the Ni and Fe contents.